CI fails in git submodule update --init --recursive for 386-linux-deb9

[Roland Senn]

Hi 

After pushing some commits, while running a CI pipeline, I persistently
get the following error for the validate-i386-linux-deb9 step:

$ git submodule update --init --recursive
fatal: Unable to create
'/builds/RolandSenn/ghc/.git/modules/libraries/Cabal/index.lock': File
exists.

Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
Unable to checkout '63331c95ed15cc7e3d83850d308dc3a86a8c3c76' in
submodule path 'libraries/Cabal'

See https://gitlab.haskell.org/RolandSenn/ghc/pipelines/11311 .

How can I fix this? I have no access to this 386 linux machine, so I'm
unable to delete the file.

Roland