When a file passed in from the command line failed to load,
blender would exit & save the quit.blend.
Resolve by adding a `do_user_exit_actions` to WM_exit_ex which is
false in backgrounds mode or when an error has occurred.
---
Back-ported [0] & [1] from main with fix [2] included.
[0]: c803ddab29
[1]: d7d1c524e3
[2]: d3d91b79e0
b2950b2ad7