Merge branch 'ab/range-diff-no-patch'

Merge branch 'ab/range-diff-no-patch'

The "--no-patch" option, which can be used to get a high-level
overview without the actual line-by-line patch difference shown, of
the "range-diff" command was earlier broken, which has been
corrected.

* ab/range-diff-no-patch:
  range-diff: make diff option behavior (e.g. --stat) consistent
  range-diff: fix regression in passing along diff options
  range-diff doc: add a section about output stability