Merge branch 'pb/range-diff-with-submodule'

"git -c diff.submodule=log range-diff" did not show anything for
submodules that changed in the ranges being compared, and
"git -c diff.submodule=diff range-diff" did not work correctly.
Fix this by including the "--submodule=short" output
unconditionally to be compared.

* pb/range-diff-with-submodule:
  range-diff: show submodule changes irrespective of diff.submodule

diff --cc range-diff.c
Simple merge