Fix issue with weird linking case crashing reprocessing

[bachtis]

There are some extreme cases where the track is propagated to the HCAL barrel entrance and then to the HCAL endcap case . It can happen to loopers . In this case an exception was thrown in linking . NOw we link those specific tracks as well but only using the first point they did hit ignoring the exit point . Ignoring the exit point just results in more strict linking which doesnt really matter because those are really low pt tracks.

[cmsbuild]

A new Pull Request was created by @bachtis (Michalis Bachtis) for CMSSW_7_6_X.

It involves the following packages:

RecoParticleFlow/PFProducer
RecoParticleFlow/PFTracking

@cmsbuild, @cvuosalo, @davidlange6, @slava77 can you please review it and eventually sign? Thanks.
@mmarionncern, @lgray this is something you requested to watch as well.
@slava77, @Degano, @smuzaffar you are the release manager for this.

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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/10481/console

[cmsbuild]

+1
Tested at: daaebab
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12930/10481/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12930/10481/summary.html

[slava77]

@bachtis please make a PR for 75X as well

[bachtis]

OK @slava77 tomorrow will do

[slava77]

+1

for #12930 daaebab

• minimal fix to crashes reported in https://hypernews.cern.ch/HyperNews/CMS/get/recoDevelopment/1411.html; only events that would otherwise have the exception thrown are affected (recovered)
• based on local tests, crash reported in event 259686:156976082 is now gone and in this event we get two warnings (expected) for this special case
• jenkins tests pass and comparisons with baseline show no differences as expected

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1