Git 1.7.7: Recent change causes buildbot to always fail to fetch from git

[cdavis5x]

When buildbot updates a repository using Git, one of the things it does is:

$ git branch -M <branch-name>

where <branch-name> is the target branch. Even if the branch already existed, this worked fine...

...up until Git 1.7.7, which for some reason changed this. Now when you try to rename the current branch, git branch -M throws this error:

fatal: Cannot force update the current branch.

Unless this bug is fixed, IT WILL NOT BE POSSIBLE TO USE BUILDBOT WITH GIT >= 1.7.7. Luckily for you all, I went ahead and fixed this for you. (Watch for an upcoming pull request.)

[dustin]

Fix is merged - thanks for spotting that!

[mattock]

I backported this patch to buildbot 0.7.12 manually, but unfortunately it did not fix the problem. What did seem to fix this was skipping the git branch -M master step conditionally:

    def _didFetch(self, res):
        if self.revision:
            head = self.revision
        else:
            head = 'FETCH_HEAD' 

        # That is not sufficient. git will leave unversioned files and empty
        # directories. Clean them up manually in _didReset.
        command = ['reset', '--hard', head]
        if self.branch == "master":
            return self._dovccmd(command, self._initSubmodules)
        else:
            return self._dovccmd(command, self._didHeadCheckout)

Didn't look deep enough in the code to know if this has some unwanted side-effects.

[dustin]

This was fixed in 6f5ce3b2ab033338f3ad7ddccbf8b6542311f70b.

[mattock]

Backported fix to buildbot 0.8.5

[mattock]

The backported fix was generated with

git-format-patch 300fbcf...6f5ce3b

It can be applied on top of buildbot installed with easy_install.