Fix way of collecting git branch names

[Konboi]

We used git rev-parse --abbrev-ref HEAD to collect a git branch name. However, in detached HEAD case, this command couldn't get a collect branch name and got HEAD. e.g) https://stackoverflow.com/questions/6059336/how-to-find-the-current-git-branch-in-detached-head-state

So, we changed to use environment variables that each CI provider provides and git show-ref | grep '^'$(git rev-parse HEAD)

[shibuiwilliam]

[question]
When does this return None?
I see the code may return "", but cannot determine None.

[Konboi]

I know your opinion but if I changed Optional[str] to str , these errors will happen

$ pipenv run type
launchable/commands/record/build.py:260: error: Incompatible return value type (got "Optional[str]", expected "str")  [return-value]
launchable/commands/record/build.py:262: error: Incompatible return value type (got "Optional[str]", expected "str")  [return-value]
launchable/commands/record/build.py:267: error: Incompatible return value type (got "Optional[str]", expected "str")  [return-value]
launchable/commands/record/build.py:269: error: Incompatible return value type (got "Optional[str]", expected "str")  [return-value]
launchable/commands/record/build.py:274: error: Incompatible return value type (got "Optional[str]", expected "str")  [return-value]

[Konboi]

Which is better 1. Keep Optional[str] 2. Change to return os.environ.get(JENKINS_GIT_BRANCH_KEY, "")?

[shibuiwilliam]

Since you are checking the env var existence in the code, then I think you can just return os.environ["KEY"].
This should return str for value of env var dict.

I suppose it is better to avoid None (or nil in Go, Null in Java) than accept None if possible.

[Konboi]

Thank you! I fixed it e448da1

[shibuiwilliam]

one question.

[sonarqubecloud]

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[basil]

Causes #581.