$ gl status
...
Tracked files with modifications:
...
  foo
...

Stop tracking changes to `foo`
$ gl untrack foo
✔ File foo is now an untracked file
Now `foo` won't be automatically considered for
commit
$ gl status
...
Untracked files:
...
  foo (exists at head)
...

Start tracking changes to `foo` again
$ gl track foo
✔ File foo is now a tracked file
Now `foo` will be automatically considered for commit
$ gl status
...
Tracked files with modifications:
...
  foo
...