Discard changes fails due to index.lock already exists

[lresende]

Description

Discard changes fails due to index.lock already exists

Reproduce

1. Go to a directory that represents cloned git repository

2. Make changes to a given file

3. Click on the icon to pull from the repository
   

4. Now, try go discard the changes in order to be able to pull from the repository
   

5. Discard fails due to index.lock is already present
   

Expected behavior

Discard should discard the changes for the file

Context

• Python package version:
  • JupyterLab 1.2.7
  • Jupyterlab-git master

Workaround

It seems that on the second try it actually behaves well, needs to investigate it further.

[lresende]

This seems related to the following git config in my environment

[branch]
        autosetuprebase = always

Maybe we could check for this and decide if we should use git merge --abort versus git rebase --abort

[fcollonval]

This should be fixed by #564