Merge branch 'dl/stash-show-untracked'

"git stash show" learned to optionally show untracked part of the
stash.

* dl/stash-show-untracked:
  stash show: learn stash.showIncludeUntracked
  stash show: teach --include-untracked and --only-untracked

diff --cc builtin/stash.c
Simple merge

diff --cc contrib/completion/git-completion.bash
Simple merge

diff --cc t/t3905-stash-include-untracked.sh
Simple merge

diff --cc unpack-trees.c
Simple merge