Paweł Czarnecki

@YuKitsune Is this PR in a state that it's working for you? I would like to patch it into a project that I'm working on and wondering if there are...

Something I noticed when trying these changes locally: `git_branch_set_upstream()` writes the config with `git_config_set_string()`, which doesn't accept a config level to write. The way the iteration works, this change returns...