Fix setting alias for "_scmb_git_branch_shortcuts"
Fix setting alias for "_scmb_git_branch_shortcuts"

__git_alias expects three arguments. Passing two arguments to __git_alias for "gb" leads to undesirable behaviour on some platforms.
ghthor/scm_breeze,dan-cleinmark/scm_breeze,scmbreeze/scm_breeze,ndbroadbent/scm_breeze,scmbreeze/scm_breeze,dan-cleinmark/scm_breeze,ghthor/scm_breeze,ndbroadbent/scm_breeze