My most recent stackage builds just had a bunch of test suite failures with the following text:
Test Cases Total test-async: Text/PrettyPrint/ANSI/Leijen.hs:(1039,1)-(1053,39): Non-exhaustive patterns in function plain
This seems to have been triggered by usage of test-framework. This is based on version 0.6.7 of the package.
Looks like it's solved to me, thanks!