tests: show EagerRepo server -> shallow client clone works

Summary:
Milestone since D64833694. Demostrate that both the server and client can talk
in the git format.

Reviewed By: zzl0

Differential Revision: D64948070

fbshipit-source-id: 89018ed95f8c3c1a389636ae93595c1cbc2389f0

eden/scm/tests/test-eager-git-exchange.t

@@ -0,0 +1,38 @@
+#require no-eden
+
+Test eager repo (client) to eager repo (server) in Git format.
+
+  $ configure modern
+
+Prepare the server repo:
+
+  $ sl init server-git --config=format.use-eager-repo=True
+  $ cd server-git
+  $ drawdag << 'EOS'
+  > A..E # bookmark master = E
+  >      # bookmark stable = C
+  > EOS
+
+Clone to a shallow client repo:
+
+  $ cd
+  $ sl clone --shallow "test:server-git" client-git
+  Cloning server-git into $TESTTMP/client-git
+  Checking out 'master'
+  5 files updated
+
+  $ cd client-git
+
+  $ cat E
+  E (no-eol)
+
+  $ sl log -Gr: -T '{desc} {remotenames}'
+  @  E remote/master
+  │
+  o  D
+  │
+  o  C
+  │
+  o  B
+  │
+  o  A