1. What happened
Imported project from Collab. Unity crashed after downloading everything and completing assets import.

2. How we can reproduce it using the example you attached
- Create project in Collab
- Download it anew from there
---> Editor crashes.

Looks like only OS X is affected. We've tried with different projects to the same result. Tried with projects created in 5.6.0b5, 5.5.1f1. Both crashed when opening in 5.6.0b5.

Uploading also system's 'Crash Dump' and Editor.log from one of previous failures as it looks a bit different.

This is a regression from 5.6.0b4