Merge branch 'maint'

* maint: blame: correctly handle a path that used to be a directory add -i: do not dump patch during application Update draft release notes for 1.6.3.2 grep: fix colouring of matches with zero length Documentation: teach stash/pop workflow instead of stash/apply Change xdl_merge to generate output even for null merges t6023: merge-file fails to output anything for a degenerate merge