Commit Briefs
log: -C requires -p
"got log -C0" is invalid synopsis, so behave accordingly.
log: Implement -s search-pattern
match_logmsg() is copied from tog's match_commit().
if there are no commits to rebase, just forward the rebased branch's reference
Problem found by kn@
Outright forbid reference names with a leading '-'.
Matches behaviour documented in git-repository(5).