"git diff" showed a submodule working tree with untracked cruft as
"Submodule commit <objectname>-dirty", but a natural expectation is
that the "-dirty" indicator would align with "git describe --dirty",
which does not consider having untracked files in the working tree
as source of dirtiness. The inconsistency has been fixed.
* sj/untracked-files-in-submodule-directory-is-not-dirty:
diff: do not show submodule with untracked files as "-dirty"