[PY3] Unit test CondCore/SiStripPlugins

[silviodonato]

@mmusich @ggovi
A unit test of CondCore/SiStripPlugins is crashing in Python3 since CMSSW_11_1_PY3_X_2020-01-28-2300 because of #28761 .

===== Test "testSiStripPayloadInspector" ====
Could not find platform independent libraries <prefix>
Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
ImportError: No module named site

---> test testSiStripPayloadInspector had ERRORS
 
^^^^ End Test testSiStripPayloadInspector ^^^^

The problems is related to boost::python used in the
CondCore/SiStripPlugins/test/testSiStripPayloadInspector.cpp

I tried to remove boost::python (see #28836) and the test is ok also in python3.
The problem arises from the method PlotBase::setInputParamValues(const boost::python::dict& values) that was integrated in CMSSW with #28648.

@davidlange6 is it allowed to use boost::python? Is there a way to make it compatible to both python 2 and 3?

[cmsbuild]

A new Issue was created by @silviodonato Silvio Donato.

@Dr15Jones, @smuzaffar, @silviodonato, @makortel, @davidlange6, @fabiocos can you please review it and eventually sign/assign? Thanks.

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[silviodonato]

assign db

[cmsbuild]

New categories assigned: db

@ggovi you have been requested to review this Pull request/Issue and eventually sign? Thanks

[silviodonato]

assign core

[cmsbuild]

New categories assigned: core

@Dr15Jones,@smuzaffar,@makortel you have been requested to review this Pull request/Issue and eventually sign? Thanks

[mmusich]

@silviodonato

The problems is related to boost::python

as far as I can see the problem is not due to boost::python in itself but rather to the Py_Initialize(), which is necessary to in order to avoid a segfault with the boost::python::dict.
Some search around in cmssw brought me to the solution at #28842 , but I am definitely not an expert so if someone with better python-fu can cross-check I would be glad.

[davidlange6]

naively we should not set PYTHONHOME by hand. Seems a missing dependency in the Buildfile?

[mmusich]

as far as I can see @smuzaffar did the same here: aff1edc ...