fix: git log should explicitly separate branch from paths

[CDN18]

The git storage module will encounter an error when a file with the same branch name exists in the root directory of the repo.

fatal: ambiguous argument 'branch_name': both revision and filename
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

This pull request will fix the problem by adding -- after the this.config.branch param of the git log command.