Fastsim 74X: fix truth matching for recoTracks from PU events

[lveldere]

required to validation digi-reco PU mixing

[lveldere]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

A new Pull Request was created by @lveldere for CMSSW_7_4_X.

Fastsim 74X: fix truth matching for recoTracks from PU events

It involves the following packages:

DataFormats/TrackerRecHit2D
SimGeneral/MixingModule

@civanch, @nclopezo, @cvuosalo, @mdhildreth, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@makortel, @VinInn, @wmtan this is something you requested to watch as well.
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@Degano you are the release manager for this.
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[cmsbuild]

-1
Tested at: 28315f6
When I ran the RelVals I found an error in the following worklfows:
25202.0 step2

runTheMatrix-results/25202.0_TTbar_13+TTbar_13+DIGIUP15_PU25+RECOUP15_PU25+HARVESTUP15_PU25+MINIAODMCUP15/step2_TTbar_13+TTbar_13+DIGIUP15_PU25+RECOUP15_PU25+HARVESTUP15_PU25+MINIAODMCUP15.log
----- Begin Fatal Exception 03-Apr-2015 15:20:23 CEST-----------------------
An exception of category 'InvalidReference' occurred while
   [0] Processing run: 1 lumi: 1 event: 1
   [1] Running path 'digitisation_step'
   [2] Calling event method for module MixingModule/'mix'
Exception Message:
Inconsistency RefCore::pushBackItem: Ref or Ptr has invalid (zero) product ID, so it cannot be added to RefVector (PtrVector). id should be (0:0)
----- End Fatal Exception -------------------------------------------------

you can see the results of the tests here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8653/4087/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8653/4885/summary.html

[cvuosalo]

+1

For #8653 cfcaad4

This PR has already been approved twice by Reco. The most recent changes are very minor and cause no problems. The Jenkins test results are contaminated by a dozen other PRs that were included.

[lveldere]

@civanch @mdhildreth
Hi Mike, Vladimir

Could you sign this one once more?

Thanks

Lukas