Enable demandimport only in scripts, not in importable modules (issue605) This way other applications can choose if and when they want this feature, because it might be problematic if those applications rely on ImportError.

# should print nothing
# should fail
abort: path 'b/x' is inside repo 'b'
abort: path 'b/x' is inside repo 'b'
# should arguably print nothing
# should fail
abort: path 'b/a' is inside repo 'b'