python: Make error message more helpful.
python: Make error message more helpful.

* lang/python/tests/run-tests.py: Make the error message shown when we
cannot locate the python module in the build tree more helpful.

Signed-off-by: Justus Winter <4d1bd7a5ca1cd26bee0df05b6801a6ce9a22196e@g10code.com>

gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme