Fix branch preview for branches that have the same name as a file

[sandr01d]

Check list

• [X] I have performed a self-review of my code
• [X] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

Description

The preview for branches (when using gbd or gcb) did not work for branches that have the same name as a file in the repository. The preview creates the following error message when adding a branch called 'LICENSE' to this repository and trying to preview it:

fatal: ambiguous argument 'LICENSE': both revision and filename                                                                                     

Use '--' to separate paths from revisions, like this:                                                                                               

'git <command> [<revision>...] -- [<file>...]'

This PR fixes this behavior by separating files and revisions with '--' as git suggests, while leaving the files blank to keep matching all files.

Type of change

• [X] Bug fix
• [ ] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [ ] bash
  • [X] zsh
  • [ ] fish
• OS
  • [X] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Others:

[carlfriedrich]

Good catch! Can reproduce the error, and the fix works for me. Thanks!