Merge branch 'pb/ref-filter-with-crlf'

A commit and tag object may have CR at the end of each and
every line (you can create such an object with hash-object or
using --cleanup=verbatim to decline the default clean-up
action), but it would make it impossible to have a blank line
to separate the title from the body of the message.  Be lenient
and accept a line with lone CR on it as a blank line, too.

* pb/ref-filter-with-crlf:
  log, show: add tests for messages containing CRLF
  ref-filter: handle CRLF at end-of-line more gracefully