Open Radar

 
Summary:
The Xcode GM seed seems to have reverted my Swift 3 project back to Swift 2.3 (i.e. it's compiling using the 2.3 compiler, instead of 3).

Steps to Reproduce:
1. I had a project that used Swift 2.3 with Xcode 7.
2. I downloaded Xcode 8 beta 1 and used the migrator to migrate to Swift 3 (successfully).
3. I downloaded the Xcode 8 betas, fixing errors as they cropped up due to new proposals.
4. I downloaded Xcode 8 GM, and the project now fails to build due to it reverting back to the 2.3 compiler when I right when opened it (I have no idea how this happened).
5. I trigger the migrator manually, which warns that the project is already on Swift 3. I force it to go through anyways, hoping to have it swap the compiler. It proposes no source changes (since I’ve already done this in previous betas) and it then “fails” for whatever reason.
6. It’s still using the old compiler and my code fails to build.

Expected Results:
The migrator at least sets the correct Swift version

Actual Results:
The conversion "fails" 

Version:
Xcode Version 8.0 (8A218a)/macOS Sierra 10.12 Beta (16A313a)

Notes:


Configuration:
Late 2011 MacBook Pro running macOS Sierra 10.12 Beta (16A313a)