Setup:

  $ . $TESTDIR/setup.sh
  $ mkdir -p ./a/bomb
  $ printf 'whatever\n' > ./a/bomb/foo.yml
  $ printf '*b/foo.yml\n' > ./.gitignore

Ignore foo.yml but not blah.yml:

  $ ag whatever .

Dont ignore anything (unrestricted search):

  $ ag -u whatever .
  a/bomb/foo.yml:1:whatever