rhg: refactor function to relativize paths in utils...
rhg: refactor function to relativize paths in utils
Commands like `files`, `status` supports printing relative paths. Hence we need
to re-use this code in other places too. So let's take this out from `rhg files`
into a utility function.
Next patch will make `rhg status` use it.
Differential Revision:
https://phab.mercurial-scm.org/D11613
