Merge branch 'jk/diff-no-index-with-pathspec'

"git diff --no-index dirA dirB" can limit the comparison with pathspec at the end of the command line, just like normal "git diff". * jk/diff-no-index-with-pathspec: diff --no-index: support limiting by pathspec pathspec: add flag to indicate operation without repository pathspec: add match_leading_pathspec variant