Merge branch 'rt/commentchar-fmt-merge-msg'

The new core.commentchar configuration was not applied to a few
places.

* rt/commentchar-fmt-merge-msg:
  fmt-merge-msg: use core.commentchar in tag signatures completely
  fmt-merge-msg: respect core.commentchar in people credits

diff --cc builtin/fmt-merge-msg.c
Simple merge

diff --cc t/t6200-fmt-merge-msg.sh
Simple merge