Merge branch 'pw/rebase-i-after-failure' into maint-2.42

Various fixes to the behaviour of "rebase -i" when the command got
interrupted by conflicting changes.
cf. <6b927687-cf6e-d73e-78fb-bd4f46736928@gmx.de>

* pw/rebase-i-after-failure:
  rebase -i: fix adding failed command to the todo list
  rebase --continue: refuse to commit after failed command
  rebase: fix rewritten list for failed pick
  sequencer: factor out part of pick_commits()
  sequencer: use rebase_path_message()
  rebase -i: remove patch file after conflict resolution
  rebase -i: move unlink() calls

diff --cc sequencer.c
Simple merge

diff --cc t/t3404-rebase-interactive.sh
Simple merge

diff --cc t/t3418-rebase-continue.sh
Simple merge

diff --cc t/t3430-rebase-merges.sh
Simple merge