Merge branch 'km/avoid-non-function-return-in-rebase' into maint

"git rebase" used a POSIX shell construct FreeBSD /bin/sh does not
work well with.

* km/avoid-non-function-return-in-rebase:
  Revert "rebase: fix run_specific_rebase's use of "return" on FreeBSD"
  rebase: avoid non-function use of "return" on FreeBSD