Updated logic in HadronAndPartonSelector

[ferencek]

Updated logic of setting the parton selector only once per job in the HadronAndPartonSelector. This PR will prevent the LogWarning from being printed out every single event when the parton selection mode is undefined.

[cmsbuild]

A new Pull Request was created by @ferencek (Dinko Ferencek) for CMSSW_7_6_X.

Updated logic in HadronAndPartonSelector

It involves the following packages:

PhysicsTools/JetMCAlgos

@cmsbuild, @vadler, @monttj can you please review it and eventually sign? Thanks.
@ferencek, @acaudron, @pvmulder, @imarches this is something you requested to watch as well.
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[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/9143/console

[cmsbuild]

+1
Tested at: d041ce0
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12060/9143/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12060/9143/summary.html