Unit tests failing without any message if linked to a framework

Setup

I've created a simple isolated case to demonstrate and reproduce the problem.

I've 2 Swift Cocoa Touch Frameworks (Lib1 & Lib2 - Lib2 is dependent on Lib1 - single swift file with single unit test in each)

Lib2 unit tests will only work if you remove the linked Lib1. Interestingly both projects works on their own if run independently.

Question: is this a bug in Xcode? any workarounds?

Files: https://www.dropbox.com/s/kycnvt1qvz8zw4o/LibTest.zip?dl=0