Nested .gitignore is not correctly applied to sub directories

[gliviu]

My directory structure:

.
├── .git
├── .gitignore        # a*
└── y
    ├── .gitignore    # !a2.txt
    ├── a2.txt        # Should not be ignored
    └── z
        └── a2.txt    # Should not be ignored.

Globby properly evaluates /y/a2.txt as included. However it fails when evaluating /z/a2.txt which is reported as ignored.

How to reproduce:
Unpack globby-issue.zip.

Run:

cd globby-issue
npm install
node main.js

Current output:

ignored  /.../globby-issue/test_dir/y/z/a2.txt
included /.../globby-issue/test_dir/y/a2.txt

Expected:

included  /.../globby-issue/test_dir/y/z/a2.txt
included /.../globby-issue/test_dir/y/a2.txt

Tested under linux with globby 13.2.2.
Looks similar to #146.