Catch ImportError if setup is run with python
Catch ImportError if setup is run with python

If setup.py is run with python instead of sage then "ImportError: No module named sage.env" happens before the KeyError.
abelfunctions/abelfunctions,cswiercz/abelfunctions,abelfunctions/abelfunctions,abelfunctions/abelfunctions,cswiercz/abelfunctions,cswiercz/abelfunctions