Using resolver nightly-2015-06-16 which is based on ghc-7.10.1 causes stack to install ghc-7.10.2 when I run stack setup.

It's also not possible to specify ghc-7.10.2 as a resolver. I can only specify ghc-7.10 which makes no sense as that's not even a real version of ghc. It doesn't mean anything as version numbers are arbitrary incremented.