test: add another regression test for gitignore matching bug

I believe this was also fixed by #2933.

Closes #2770

CHANGELOG.md

@@ -12,6 +12,7 @@ Bug fixes:
 * [BUG #829](https://github.com/BurntSushi/ripgrep/issues/829),
   [BUG #2731](https://github.com/BurntSushi/ripgrep/issues/2731),
   [BUG #2747](https://github.com/BurntSushi/ripgrep/issues/2747),
+  [BUG #2770](https://github.com/BurntSushi/ripgrep/issues/2770),
   [BUG #2778](https://github.com/BurntSushi/ripgrep/issues/2778),
   [BUG #2836](https://github.com/BurntSushi/ripgrep/issues/2836),
   [BUG #2933](https://github.com/BurntSushi/ripgrep/pull/2933),