Merge branch 'js/rebase-count-fixes'

A few bugs in the sequencer machinery that results in miscounting
the steps have been corrected.

* js/rebase-count-fixes:
  rebase -r: fix the total number shown in the progress
  rebase --update-refs: fix loops

diff --cc sequencer.c
Simple merge

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