add checks if trajectory has hits before accessing them

[slava77]

fixes crashes in refittedStandAloneMuons observed in 750pre4 and pre5

[cmsbuild]

A new Pull Request was created by @slava77 (Slava Krutelyov) for CMSSW_7_5_X.

add checks if trajectory has hits before accessing them

It involves the following packages:

TrackingTools/TrackFitters

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
@battibass, @makortel, @abbiendi, @GiacomoSguazzoni, @jhgoh, @VinInn, @appeltel, @bellan, @rovere, @cerati, @gpetruc, @istaslis, @trocino, @dgulhan, @venturia 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.

[slava77]

+1

for #9602 1118cf6

• crash reported in https://hypernews.cern.ch/HyperNews/CMS/get/relval/3728.html is fixed (the code processes the problematic event)
• local short matrix tests were done with CMSSW_7_5_0_pre5 /test area fixMuRefit/. Comparisons with baseline show no differences as expected (the changed part of the code can possibly behave differently if the baseline was crashing, but that doesn't happen in the set of tests running).

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-9602/5471/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1