Fix for reweighting not running if f2py not available

Hannes Mildner requested to merge hmildner/athena:21.6-MG-rwgt-f2py-fix into 21.6

The MG reweighting module requires f2py. Otherwise it does not run (but also doesn't throw an error). In (some?) releases f2py is not available and the executable is called f2py2 instead. This fix checks whether f2py is available. If not it tells MadGraph to use f2py2. If this is not available it throws an error. See also AGENE-1771.

Merge request reports