Merge branch 'pw/rebase-i-regression-fix-tests' into maint

Fix a recent regression to "git rebase -i" and add tests that would
have caught it and others.

* pw/rebase-i-regression-fix-tests:
t3420: fix under GETTEXT_POISON build
rebase: add more regression tests for console output
rebase: add regression tests for console output
rebase -i: add test for reflog message
sequencer: print autostash messages to stderr

diff --cc git-rebase.sh
Simple merge

diff --cc sequencer.c
Simple merge

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