Jenkins tb76-maggie crashed/hung git

[Lionel Elie Mamane]

See
https://ci.libreoffice.org/job/gerrit_linux_clang_dbgutil/19386/console

Checking out Revision dfd105903b22b33956cf571fd4c722c829f7c997 (refs/changes/69/62969/2)
 > git config core.sparsecheckout # timeout=10
 > git checkout -f dfd105903b22b33956cf571fd4c722c829f7c997 # timeout=30
hudson.plugins.git.GitException: Command "git checkout -f dfd105903b22b33956cf571fd4c722c829f7c997" returned status code 128:
stdout: 
stderr: fatal: Unable to create '/home/tdf/lode/jenkins/workspace/lo_gerrit/Config/linux_clang_dbgutil_64/.git/index.lock': File exists.

If no other git process is currently running, this probably means a
git process crashed in this repository earlier. Make sure no other git
process is running and remove the file manually to continue.