Merge branch 'pw/rebase-fixup-fixes' into next

Two bugs in how 'git rebase' handles skipped 'fixup' and 'squash'
commands have been fixed.  One bug caused an incorrect commit count to
be shown in the template message when multiple commands were skipped,
and another prevented the editor from opening when the final command
in a chain containing 'fixup -c' was skipped.

* pw/rebase-fixup-fixes:
  rebase: remember fixup -c after skipping fixup/squash
  rebase -i: fix counting of fixups after rebase --skip

diff --cc sequencer.c
Simple merge

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