A handful of obvious clean-ups around a topic that is already in
'master'.
* gc/branch-recurse-submodules-fix:
branch.c: simplify advice-and-die sequence
branch: rework comments for future developers
branch: remove negative exit code
branch --set-upstream-to: be consistent when advising
branch: give submodule updating advice before exit
branch: support more tracking modes when recursing
projects / thirdparty / git.git / commit
