Add support for AnalysisBaseExternals Python 2.7 and Python 3 in same environment (!29)

Resolves #4 (closed)

Unset PYTHONHOME and PYTHONPATH and add supporting Python .pth file

As PYTHONHOME and PYTHONPATH are unset then a AnalysisBaseExternals_python2.pth file needs to be added for the AnalysisBase Externals Python 2.7 to be used along with ROOT in the same environment as Python 3

changed title from WIP: Unset PYTHONHOME and PYTHONPATH and add supporting Python .pth file to WIP: Unset PYTHONHOME and PYTHONPATH and add supporting Python .pth file (!29)

changed title from WIP: Unset PYTHONHOME and PYTHONPATH and add supporting Python .pth file (!29 (merged)) to WIP: Add support for AnalysisBaseExternals Python 2.7 and Python 3 in same environment (!29 (merged))

changed the description

So this works? Wow it's actually pretty simple.

unmarked as a Work In Progress

changed the description

So this works? Wow it's actually pretty simple.

@dguest, yup. The hard part was finding out what of the things that ended up getting shoved into PYTHONPATH by /home/atlas/release_setup.sh actually controlled if Python 2 knew what it and ROOT was. This I stupidly did through trial and error.

mentioned in commit e73c220b

merged