Missing gc.log.lock during updating a tracked branch

[vkpgwt]

Hello!

I created a repo in critic, setup tracking the 'develop' branch, and created reviews for three remote branches. It worked fine, but 10 hours later I got the following traceback:

2018-02-01 11:13:11,169 - ERROR -   update of branch r/medium-priority-bugfixes from medium-priority-bugfixes in http://critic:[email protected]/myrepo failed
    Traceback (most recent call last):
      File "/usr/share/critic/background/branchtracker.py", line 170, in update
        self.debug("  fetched %s in %s; no changes" % (remote_name, remote))
      File "/usr/share/critic/gitutils.py", line 637, in __exit__
        shutil.rmtree(self.path)
      File "/usr/lib/python2.7/shutil.py", line 247, in rmtree
        rmtree(fullname, ignore_errors, onerror)
      File "/usr/lib/python2.7/shutil.py", line 252, in rmtree
        onerror(os.remove, fullname, sys.exc_info())
      File "/usr/lib/python2.7/shutil.py", line 250, in rmtree
        os.remove(fullname)
    OSError: [Errno 2] No such file or directory: '/var/lib/critic/relay/myrepo_branchtracker_yOLPcJ/myrepo.git/gc.log.lock'

Critic version: 28ed20bb8032d7cc5aa23de98da51e619fd84164

Then I triggered a manual update of the branch and it was done successfully (the remote branch hadn't changed, though).