I don't think the checked-in file with `.gitignore` works how you're expecting:

```bash
pg-shrink(master)$ gst
## master
pg-shrink(master)$ ag 'yml' .gitignore
24:spec/pg_config.yml
pg-shrink(master)$ echo 'foo' >> spec/pg_config.yml
pg-shrink(master)$ gst
## master
 M spec/pg_config.yml
```

`.gitignore` only prevents files from being added to the repository at all. To my knowledge, there's no good way to tell Git to ignore changes to a file from that point on.