git stash --include-untracked walks ignored directories

[Brian Malehorn <bmalehorn@gmail.com>]

Hi,

Not sure if this is the right place to send this, but I'm here to
report a performance regression with git stash --include-untracked.

Here's a quick way to reproduce:

1. make a directory with a lot of ignored files

$ find ignored -type f | wc -l
   50000

$ cat .gitignore
ignored

2. touch foo

3. time git stash --include-untracked

git version 2.26.0:
real    0m0.094s

git version 2.27.0.83.g0313f36c6e:
real    0m1.913s

This is a much bigger pain point on my work repo, which has 1.4
million ignored files(!). As you can imagine it takes a long time to
run git stash. While it might be valid to question why anyone would
need that many files for any purpose, the bottom line is that I told
git to ignore this directory, and it didn't ignore it.

In the meantime I've reverted to 2.26.0 which doesn't have this
performance regression. Let me know if you want any other information
related to this issue.

Thanks,
Brian