UPDATE: FIXED! See sol/doctest#167 (comment)
Just stack test
and see:
$ stack test
docbug-0.1.0.0: test (suite: doctests)
src/SomeLib.hs:5:1: error: parse error on input ‘import’
Test suite failure for package docbug-0.1.0.0
doctests: exited with: ExitFailure 1
Logs printed to console