F2PY can generate inconsistent suffix for *.so files due to a
different version of numpy if not the same as the one used
in the virtualenv. The workaround is to remove the
"cpython-36m-x86_64-linux-gnu"-like part of the name. The import
mechanism works well without. This is a tiny hack though.
The f2py *.so suffix is not consistent with python virtualenv version.
By using the source dir it is easier to fix manually since the *.so are not
installed
Sylvain Tricot