"git diff --color-moved --cc --stat -p" did not work well due to
funny interaction between a bug in color-moved and the rest, which
has been fixed.
* jk/diff-cc-stat-fixes:
combine-diff: treat --dirstat like --stat
combine-diff: treat --summary like --stat
combine-diff: treat --shortstat like --stat
combine-diff: factor out stat-format mask
diff: clear emitted_symbols flag after use
t4006: resurrect commented-out tests