confused about git clone --mirror

[KayGau]

Audris,
I am working on batch_fetch.c now. However, I meet a problem about git clone --mirror.
When using git clone --mirror and git fetch --all (on scikit-learn), here is the output:

Fetching origin
remote: Enumerating objects: 10529, done.
remote: Counting objects: 100% (8652/8652), done.
remote: Compressing objects: 100% (4079/4079), done.
remote: Total 7868 (delta 6189), reused 5115 (delta 3762), pack-reused 0
Receiving objects: 100% (7868/7868), 1.69 MiB | 138.00 KiB/s, done.
Resolving deltas: 100% (6189/6189), completed with 406 local objects.
From https://github.com/scikit-learn/scikit-learn
   d163d5ad94..2287d2d229  master                -> master
 + 4c6f42ccd2...8d88b41cfe refs/pull/10775/merge -> refs/pull/10775/merge  (forced update)
 + c89bff7ddc...2299d5ee27 refs/pull/10931/merge -> refs/pull/10931/merge  (forced update)
 + fced5f7aed...1ccf7273f8 refs/pull/11116/merge -> refs/pull/11116/merge  (forced update)
 + 13b9022ec9...36bf759326 refs/pull/11274/merge -> refs/pull/11274/merge  (forced update)
 + 4b1eec039a...4455e1a6e5 refs/pull/11305/merge -> refs/pull/11305/merge  (forced update)
 + e86235c6fc...c0426b0c73 refs/pull/11430/merge -> refs/pull/11430/merge  (forced update)
 + 8b75cf9216...5a79f335bc refs/pull/11541/merge -> refs/pull/11541/merge  (forced update)
 + 24c82d2330...447abce666 refs/pull/11707/merge -> refs/pull/11707/merge  (forced update)
 + bc5e404563...7b605c9639 refs/pull/11723/merge -> refs/pull/11723/merge  (forced update)
 + c3b43c23e6...8399757407 refs/pull/12316/merge -> refs/pull/12316/merge  (forced update)
 + 6b47fea112...00460640f7 refs/pull/12319/merge -> refs/pull/12319/merge  (forced update)
 + d72d602280...c8ca636e85 refs/pull/13003/merge -> refs/pull/13003/merge  (forced update)
 + 125dc6034a...d864065317 refs/pull/13204/merge -> refs/pull/13204/merge  (forced update)
 + fff6dfc1ac...f90b7c800e refs/pull/13900/merge -> refs/pull/13900/merge  (forced update)
 + fd3fbad58b...5d6f5f0c5f refs/pull/14075/merge -> refs/pull/14075/merge  (forced update)
 + 2c8ded448a...2735ee032a refs/pull/14446/merge -> refs/pull/14446/merge  (forced update)
 + bc40dedb0e...a1f69b564e refs/pull/14466/merge -> refs/pull/14466/merge  (forced update)
 + f93dae54c7...2f3397b1a2 refs/pull/14488/merge -> refs/pull/14488/merge  (forced update)
 + b2d8a13153...0597d7f2c6 refs/pull/14524/merge -> refs/pull/14524/merge  (forced update)
 + d90369a075...9b558da6a1 refs/pull/14616/merge -> refs/pull/14616/merge  (forced update)
 + de30d639ac...ca4b54b987 refs/pull/14620/merge -> refs/pull/14620/merge  (forced update)
 + c44f3eef5d...c0ee3561e1 refs/pull/14622/merge -> refs/pull/14622/merge  (forced update)
 + be729ce5fa...6cc171538b refs/pull/14643/merge -> refs/pull/14643/merge  (forced update)
 + 8a6b18eef0...1dd0ae298d refs/pull/14654/merge -> refs/pull/14654/merge  (forced update)
 + 5ed3e87a87...12f9444fb6 refs/pull/14663/merge -> refs/pull/14663/merge  (forced update)
 + de3a4bede6...9448f63303 refs/pull/14675/merge -> refs/pull/14675/merge  (forced update)
 + 111a889aab...35cec8bc32 refs/pull/14698/merge -> refs/pull/14698/merge  (forced update)
 + 285a6e39e9...a7a246269d refs/pull/14748/merge -> refs/pull/14748/merge  (forced update)
 + 6ae14500f4...2c095fa9e9 refs/pull/14757/merge -> refs/pull/14757/merge  (forced update)
 + e80c8d41b5...8536927d34 refs/pull/14800/merge -> refs/pull/14800/merge  (forced update)
 + ec2787c9d8...babb46583f refs/pull/14820/merge -> refs/pull/14820/merge  (forced update)
 + 2dc6bd7c51...fe0c02eb64 refs/pull/14822/merge -> refs/pull/14822/merge  (forced update)
 + 8eabad8a80...a346c8f510 refs/pull/14848/merge -> refs/pull/14848/merge  (forced update)
 + 6f21e9f19e...1a93fd0309 refs/pull/14867/merge -> refs/pull/14867/merge  (forced update)
 + 0fd7464800...e29e3a1e66 refs/pull/14873/merge -> refs/pull/14873/merge  (forced update)
 + a469f6f86a...7d0516c0f2 refs/pull/14980/merge -> refs/pull/14980/merge  (forced update)
 + 2d5e80026b...697cc57eb6 refs/pull/14982/merge -> refs/pull/14982/merge  (forced update)
 + 446a249f4b...99ecbf88d0 refs/pull/14984/merge -> refs/pull/14984/merge  (forced update)
 + d0622abd1d...ca9e534b3f refs/pull/14992/merge -> refs/pull/14992/merge  (forced update)
 + 8f903beefa...c336fd4de4 refs/pull/15015/merge -> refs/pull/15015/merge  (forced update)
 + 14b8acf710...9361867a45 refs/pull/15032/merge -> refs/pull/15032/merge  (forced update)
 + f09c36b3af...51d5f322e8 refs/pull/15050/merge -> refs/pull/15050/merge  (forced update)
 + 6ac364084f...b20bd6e8d4 refs/pull/15054/merge -> refs/pull/15054/merge  (forced update)
 + 866ba6d662...b29a604a5c refs/pull/15069/merge -> refs/pull/15069/merge  (forced update)
 + 8c548adbc2...f59e649c3b refs/pull/15126/merge -> refs/pull/15126/merge  (forced update)
 + c6d54e71f6...acb083dbbe refs/pull/15134/merge -> refs/pull/15134/merge  (forced update)
 + 0e13545d9b...19c02a8912 refs/pull/15167/merge -> refs/pull/15167/merge  (forced update)
 + 98355d842b...2878b69d17 refs/pull/15177/merge -> refs/pull/15177/merge  (forced update)
 + 6d590cca8a...896c9d1d15 refs/pull/15179/merge -> refs/pull/15179/merge  (forced update)
 + da5ecf27f6...70299b42ff refs/pull/15189/merge -> refs/pull/15189/merge  (forced update)
 + 24c1da4297...c044e38083 refs/pull/15193/merge -> refs/pull/15193/merge  (forced update)
 + 68e86c9aa3...cd2d371a3a refs/pull/15210/merge -> refs/pull/15210/merge  (forced update)
 + 5a26440ead...514103e9ee refs/pull/15211/merge -> refs/pull/15211/merge  (forced update)
 + f6bb4a30e6...61600c4697 refs/pull/15215/merge -> refs/pull/15215/merge  (forced update)
 + 4410fa5984...5c2a0bf016 refs/pull/15218/merge -> refs/pull/15218/merge  (forced update)
 + 0adfda65a1...9482e19ffd refs/pull/15221/merge -> refs/pull/15221/merge  (forced update)
 + bae23c2457...4961ce28bd refs/pull/15226/merge -> refs/pull/15226/merge  (forced update)
 + 71e7e63c5c...67c76bea29 refs/pull/15228/merge -> refs/pull/15228/merge  (forced update)
 + 5c129e2ae5...19090e73a9 refs/pull/15229/merge -> refs/pull/15229/merge  (forced update)
 + d07ebf7f70...c0cb838345 refs/pull/15230/merge -> refs/pull/15230/merge  (forced update)
 + 25705d2dd4...99106e9893 refs/pull/15239/merge -> refs/pull/15239/merge  (forced update)
 + c74b541765...909b8f442b refs/pull/15246/merge -> refs/pull/15246/merge  (forced update)
 + c330d80428...44fd96269b refs/pull/15300/merge -> refs/pull/15300/merge  (forced update)
 + 19712167ed...023524321d refs/pull/15361/merge -> refs/pull/15361/merge  (forced update)
 + 9eb5d538dd...7c17618a46 refs/pull/15386/merge -> refs/pull/15386/merge  (forced update)
 + b1c11b75f4...d28d1e6878 refs/pull/15401/merge -> refs/pull/15401/merge  (forced update)
 + 8f6913605a...ef62a85405 refs/pull/15403/merge -> refs/pull/15403/merge  (forced update)
 + c9e4144dbc...b600f9829d refs/pull/15412/merge -> refs/pull/15412/merge  (forced update)
 + 65683eebb5...74a4a64ba7 refs/pull/15427/merge -> refs/pull/15427/merge  (forced update)
 + e689a8bdc4...5c379eeaf4 refs/pull/15447/merge -> refs/pull/15447/merge  (forced update)
 + ca44bfee24...0fc53c0f4d refs/pull/15452/merge -> refs/pull/15452/merge  (forced update)
 + 878f973c85...bf3cad873e refs/pull/15457/merge -> refs/pull/15457/merge  (forced update)
 + eb295dff83...00eb36d5a8 refs/pull/15460/merge -> refs/pull/15460/merge  (forced update)
 + c99256f0d5...3ff50f22df refs/pull/15477/merge -> refs/pull/15477/merge  (forced update)
 + 2e76ee2036...b61f6cd76d refs/pull/15489/merge -> refs/pull/15489/merge  (forced update)
 + 3b3b48da92...ab47713496 refs/pull/15504/merge -> refs/pull/15504/merge  (forced update)
 + 2faa4d7555...3adf5eba24 refs/pull/15514/merge -> refs/pull/15514/merge  (forced update)
 + 1e12864f9f...2fcca85d01 refs/pull/15517/merge -> refs/pull/15517/merge  (forced update)
 + 54ed0e7a8c...a8be6e6192 refs/pull/15522/merge -> refs/pull/15522/merge  (forced update)
 + e71204f625...478ea3ec26 refs/pull/15526/merge -> refs/pull/15526/merge  (forced update)
 + 33a5433a8b...7ae4f5f916 refs/pull/15528/merge -> refs/pull/15528/merge  (forced update)
 + 075fa642f1...cfa6c74f08 refs/pull/15529/merge -> refs/pull/15529/merge  (forced update)
 + eb1c852360...3a12cb4451 refs/pull/15549/merge -> refs/pull/15549/merge  (forced update)
 + e76dcf22f1...888170d123 refs/pull/15575/merge -> refs/pull/15575/merge  (forced update)
 + adcbca22f6...77878a2abc refs/pull/15576/merge -> refs/pull/15576/merge  (forced update)
 + a679becc67...af740d99f7 refs/pull/15582/merge -> refs/pull/15582/merge  (forced update)
 + 346c550949...cb3409152f refs/pull/15586/merge -> refs/pull/15586/merge  (forced update)
 + 705bd66c61...1b3c484413 refs/pull/15613/merge -> refs/pull/15613/merge  (forced update)
 + 0cdb8bd45a...480ffa36a8 refs/pull/15635/merge -> refs/pull/15635/merge  (forced update)
 + 3bdd1bccdc...c156696a1c refs/pull/15636/merge -> refs/pull/15636/merge  (forced update)
 + 8ba91ce1b5...f0d848ca21 refs/pull/15650/merge -> refs/pull/15650/merge  (forced update)
 + f1e31fa102...e0aaabea24 refs/pull/15668/merge -> refs/pull/15668/merge  (forced update)
 + ac3f5af3af...69223394ae refs/pull/15669/merge -> refs/pull/15669/merge  (forced update)
 + 1c3edb2fc3...1573365f66 refs/pull/15673/merge -> refs/pull/15673/merge  (forced update)
 + baff33c578...7d22da3916 refs/pull/15689/merge -> refs/pull/15689/merge  (forced update)
 + 1a84255b6e...5260c08c65 refs/pull/15691/merge -> refs/pull/15691/merge  (forced update)
 + ad31344c9d...c4f9669e26 refs/pull/15706/merge -> refs/pull/15706/merge  (forced update)
 + f9786ede77...b30d255f01 refs/pull/15710/merge -> refs/pull/15710/merge  (forced update)
 + 90eed382ea...e1b7a4cbd4 refs/pull/15719/merge -> refs/pull/15719/merge  (forced update)
 + 527a4416f3...743b3b70c7 refs/pull/15725/merge -> refs/pull/15725/merge  (forced update)
 + 404a325293...72ed274e00 refs/pull/15734/merge -> refs/pull/15734/merge  (forced update)
 + 5c6e951ab9...856c62755f refs/pull/15737/merge -> refs/pull/15737/merge  (forced update)
 + f1e1e68e41...0201bf1ad9 refs/pull/15744/merge -> refs/pull/15744/merge  (forced update)
 + cbde645141...7f2ae88e01 refs/pull/15759/merge -> refs/pull/15759/merge  (forced update)
 + b6af02ec6c...51df5af54e refs/pull/15763/merge -> refs/pull/15763/merge  (forced update)
 + d83155a20b...5ed189e06e refs/pull/15776/merge -> refs/pull/15776/merge  (forced update)
 + 85549fabbb...46e7110084 refs/pull/15782/merge -> refs/pull/15782/merge  (forced update)
 + 1853b1c5ec...78b6eda488 refs/pull/15798/merge -> refs/pull/15798/merge  (forced update)
 + dbb2e96d2c...0ef12c6957 refs/pull/15815/merge -> refs/pull/15815/merge  (forced update)
 + b0b7de58f8...f28bf38b9c refs/pull/15856/merge -> refs/pull/15856/merge  (forced update)
 + bf30ee86ca...bc85aa17be refs/pull/15857/merge -> refs/pull/15857/merge  (forced update)
 + 41791af204...ee2b860bdc refs/pull/15860/merge -> refs/pull/15860/merge  (forced update)
 + 858bc6a31c...27422c6e19 refs/pull/15863/merge -> refs/pull/15863/merge  (forced update)
 + ccccc56bf1...e7d946c1a1 refs/pull/15906/merge -> refs/pull/15906/merge  (forced update)
 + 0d6fdca33a...4390598853 refs/pull/15907/merge -> refs/pull/15907/merge  (forced update)
 + b6165fb4f0...7273f4f056 refs/pull/15931/merge -> refs/pull/15931/merge  (forced update)
 + 9e7cfc3a90...8810b922f6 refs/pull/15934/merge -> refs/pull/15934/merge  (forced update)
 + 4eeb654f18...8b879bf47e refs/pull/15937/merge -> refs/pull/15937/merge  (forced update)
 + d0711f02ba...d64118622c refs/pull/15940/merge -> refs/pull/15940/merge  (forced update)
 + 37ae36b4c1...8866910377 refs/pull/15948/merge -> refs/pull/15948/merge  (forced update)
 + 373eb3c59d...058b378e76 refs/pull/15952/merge -> refs/pull/15952/merge  (forced update)
 + dbef5ddd46...2684357f9b refs/pull/15954/merge -> refs/pull/15954/merge  (forced update)
 + b0cae5ef5d...7757095a22 refs/pull/15955/merge -> refs/pull/15955/merge  (forced update)
 + fae5f35010...901e2219ba refs/pull/15959/merge -> refs/pull/15959/merge  (forced update)
 + 1203aaed0e...13aec1b54d refs/pull/15962/merge -> refs/pull/15962/merge  (forced update)
 + 8016f2febc...7843c30105 refs/pull/15963/merge -> refs/pull/15963/merge  (forced update)
 + ae7d03167f...bed53d2f49 refs/pull/15971/merge -> refs/pull/15971/merge  (forced update)
 + a1e908dc56...82482bb775 refs/pull/15973/merge -> refs/pull/15973/merge  (forced update)
 + c9c9399e85...db161fad26 refs/pull/15974/merge -> refs/pull/15974/merge  (forced update)
 + 37db6e5af9...2f1f1374ec refs/pull/15975/merge -> refs/pull/15975/merge  (forced update)
 + 6a9cae16f0...8354a2b749 refs/pull/4289/merge  -> refs/pull/4289/merge  (forced update)
 + a023191556...c539ab05b4 refs/pull/5172/merge  -> refs/pull/5172/merge  (forced update)
 + d8e34b0309...7f07c82061 refs/pull/6236/merge  -> refs/pull/6236/merge  (forced update)
 + 70da2e02c9...ffd47a799b refs/pull/6338/merge  -> refs/pull/6338/merge  (forced update)
 + a43448f0bd...419741ac97 refs/pull/7284/merge  -> refs/pull/7284/merge  (forced update)
 + c0f8d88fc0...a6d52f53e9 refs/pull/8230/merge  -> refs/pull/8230/merge  (forced update)
 + 6bf8ffeeab...78171f3a6a refs/pull/9398/merge  -> refs/pull/9398/merge  (forced update)
 + ef765d4069...26101dadb7 refs/pull/9555/merge  -> refs/pull/9555/merge  (forced update)
 + 6430540ef0...a0f41d4eae refs/pull/9605/merge  -> refs/pull/9605/merge  (forced update)
 + 27fa6fdbec...ad0038eb13 refs/pull/9822/merge  -> refs/pull/9822/merge  (forced update)

However, except for the first ( d163d5ad94..2287d2d229 master -> master), the others' commit doesn't appear in the scikit-learn's commit page! Besides, all these branches doesn't exist in scikit-repo!
When using git clone and git fetch, the behavior is exactly the same as the repo.

[KayGau]

I also investigate why git clone --mirror and git fetch --all behaves like these. Take + c9c9399e85...db161fad26 refs/pull/15974/merge -> refs/pull/15974/merge (forced update) as an example:

$ git cat-file -p db161fad26          
tree 9b9b04c524d1c5310730dacd4046ccede0f3621a
parent 2287d2d229b763c7592127106c8947872e7326c2
parent 7b0b4ca388ca2b2f0e8bdd4f9269b5595f3b27f5
author @nkish <[email protected]> 1577444341 +0100
committer GitHub <[email protected]> 1577444341 +0100
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Merge 7b0b4ca388ca2b2f0e8bdd4f9269b5595f3b27f5 into 2287d2d229b763c7592127106c8947872e7326c2
$ git cat-file -p c9c9399e85          
tree 3480b638e1281815b373fc9b0422926bb4f2633c
parent 74a08746d471b08463ff79c417246f58d54fec5d
parent 7b0b4ca388ca2b2f0e8bdd4f9269b5595f3b27f5
author @nkish <[email protected]> 1577378237 +0530
committer GitHub <[email protected]> 1577378237 +0530
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Merge 7b0b4ca388ca2b2f0e8bdd4f9269b5595f3b27f5 into 74a08746d471b08463ff79c417246f58d54fec5d

2287d2d229b763c7592127106c8947872e7326c2 is newer than 74a08746d471b08463ff79c417246f58d54fec5d;
7b0b4ca388ca2b2f0e8bdd4f9269b5595f3b27f5 is an commit of scikit-learn's pull request #15974's last commit, see: https://github.com/scikit-learn/scikit-learn/pull/15974/commits (also a commit in https://github.com/ankishb/scikit-learn/commits/feature_ext, a fork repo of scikit-learn), not a commit in scikit-learn.
So I think those refs/pull/* are not a part of true scikit-learn.
I think git clone and git fetch --all behave the same as the true scikit-learn's development activity

[KayGau]

I think it is caused by github's pull request mechanism. But, the packed-refs is correct