[SSSD] [sssd PR#653][opened] sbus: dectect python binary for sbus_generate.sh

[sumit-bose]

   URL: https://github.com/SSSD/sssd/pull/653
Author: sumit-bose
 Title: #653: sbus: dectect python binary for sbus_generate.sh
Action: opened

PR body:
"""
We already detect python2 and python3 binaries during configure. With
this patch PYTHON_EXEC is set to the python3 binary if python3 bindings
are generated and to the python2 binary otherwise. With the help of an
environment variable sbus_generate.sh is made aware of it.

Related to https://pagure.io/SSSD/sssd/issue/3807
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/653/head:pr653
git checkout pr653