Merge branch 'dl/stash-show-untracked-fixup'

The code to handle options recently added to "git stash show" around untracked part of the stash segfaulted when these options were used on a stash entry that does not record untracked part. * dl/stash-show-untracked-fixup: stash show: fix segfault with --{include,only}-untracked t3905: correct test title