Merge branch 'jc/retire-compaction-heuristics'

"git diff" and its family had two experimental heuristics to shift the contents of a hunk to make the patch easier to read. One of them turns out to be better than the other, so leave only the "--indent-heuristic" option and remove the other one. * jc/retire-compaction-heuristics: diff: retire "compaction" heuristics