Stacktrace when loading plugin installed in 'develop' mode

Loading a plugin installed through pip install -e or setup.py develop results in particularly cryptic error messages: pip_e.txt.

Since users writing plugins will presumably often use this method of installation for convenience, this error should either be fixed or at least result in a slightly more understandable error message.

mentioned in merge request !107 (closed)

Fixed by merge of !107 (closed)

closed