Bug fix on infinite loop in MuonSinClassifier (Backport)

[srimanob]

PR description:

As reported in https://its.cern.ch/jira/browse/CMSMUONS-312, infinite loop happens in the RECOSIM step, because Gen Muons appear as the first GenParticle in the tree.

This fixes the issue.

Backport #28802

PR validation:

Local test with DR step of
https://cms-pdmv.cern.ch/mcm/chained_requests?contains=PPS-RunIIFall18GS-00004&page=0&shown=15

if this PR is a backport please specify the original PR and why you need to backport that PR:

#28802

[cmsbuild]

A new Pull Request was created by @srimanob (Phat Srimanobhas) for CMSSW_10_2_X.

It involves the following packages:

SimMuon/MCTruth

@cmsbuild, @civanch, @mdhildreth can you please review it and eventually sign? Thanks.
@battibass, @abbiendi, @jhgoh, @calderona, @HuguesBrun, @Fedespring, @cericeci, @trocino, @folguera this is something you requested to watch as well.
@davidlange6, @silviodonato, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[civanch]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/4948/console Started: 2020/03/02 09:58

[cmsbuild]

+1
Tested at: 0b539aa
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-551244/4948/summary.html
CMSSW: CMSSW_10_2_X_2020-03-01-2300
SCRAM_ARCH: slc6_amd64_gcc700

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-551244/4948/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 2 differences found in the comparisons
• DQMHistoTests: Total files compared: 31
• DQMHistoTests: Total histograms compared: 3007491
• DQMHistoTests: Total failures: 3
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3007298
• DQMHistoTests: Total skipped: 190
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 30 files compared)
• Checked 129 log files, 14 edm output root files, 31 DQM output files

[civanch]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_10_2_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_11_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @silviodonato, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[silviodonato]

+1
@srimanob I guess we will need a backport for 10_6_X as well

[srimanob]

+1
@srimanob I guess we will need a backport for 10_6_X as well

Hi, here it is
#29071
thx.