Strange parse error when no import present

[flip111]

code:

-- |
-- prop> foo == 2
foo = 2

main = putStrLn "dummy"

shell:

» doctest Foo.hs

Foo.hs:3:1: parse error on input ‘foo’

This does not happen when the program start with import GHC.OldList (nub) see https://github.com/sol/doctest/issues/122 for that