Merge branch 'js/rebase-i-commentchar-fix'

"git rebase -i" did not work well with core.commentchar
configuration variable for two reasons, both of which have been
fixed.

* js/rebase-i-commentchar-fix:
  rebase -i: handle core.commentChar=auto
  stripspace: respect repository config
  rebase -i: highlight problems with core.commentchar

diff --cc git-rebase--interactive.sh
Simple merge

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