Bug: path splitter gets removed if no path spec exists

[thomaszub]

Hi,

I have currently the issue, that the path splitter -- is removed if no path spec exists, e.g. git checkout -f dev -- becomes git checkout -f dev.
This can be an issue if for example in a repository with a file dev, no local branch dev and a remote branch origin/dev. The checkout command can not decide which operation to perform (create local branch or restore file) and quits with an error.
This can be reproduced in the repository: https://github.com/thomaszub/simple-git-co-bug

I make a PR.

Kind regards
Thomas

[steveukx]

Hi, thank you for the pull request. You can now use this feature as part of the 3.19.1 release which is available on npm now.