Bug: stash save -u removes (some) ignored files

I have seen the following problem:

felipe@felipe:testgit% cat .gitignore **/notrack/* !**/notrack/track/ notrackfile**

felipe@felipe:testgit% find * newfile notrack notrack/1 notrackfile1

felipe@felipe:testgit% git status --porcelain ?? newfile

felipe@felipe:testgit% git stash save -u Saved working directory and index state WIP on master: 523cb39 Initial commit HEAD is now at 523cb39 Initial commit

felipe@felipe:testgit% find * notrackfile1

So, after a stash save, git decided to keep the untracked file in the current directory, but not the ones inside the untracked directory. However, the files were "correctly" ignored and did not appear on the stash:

felipe@felipe:testgit% git stash pop
Already up-to-date!
On branch master
Untracked files:
  (use "git add <file>..." to include in what will be committed)

        newfile

nothing added to commit but untracked files present (use "git add" to track) Dropped refs/stash@{0} (e6508f345af1dd207557ad0291e7e3bce8a89b1e)

felipe@felipe:testgit% find * newfile notrackfile1

I think the correct behaviour should be to left the ignored files untouched in both scenarios.

This is with git 2.6.1 (from debian).

I note that if I add a file inside the notrack/track directory, it is correctly kept, but the files in notrack/ are still deleted.