Merge branch 'ps/dash-buggy-0.5.13-workaround' into next

The way dash 0.5.13 handles non-ASCII contents in here-doc
is buggy and breaks our existing tests, which unfortunately
have been rewritten to avoid triggering the bug.

* ps/dash-buggy-0.5.13-workaround:
  t9300: work around partial read bug in Dash v0.5.13
  t: work around multibyte bug in quoted heredocs with Dash v0.5.13

diff --cc t/t4014-format-patch.sh
Simple merge

diff --cc t/t9001-send-email.sh
Simple merge