Issue #3868: Refactor the logic about diff in a single place - pagure

pagure

#3868 Refactor the logic about diff in a single place

Closed: Fixed Dec 4, 2018 Opened Oct 9, 2018 by pingou.

Currently, the logic to determine if a file was added/modified/deleted is present in three places:
- repo_pull_request.html
- _repo_renderdiff.html
- pagure.api.forks.py

We should re-factor this to have it in one place (potentially, pagure.lib.git) which we could then call from the API as well as from a Jinja filters to be used in the templates.