add a nan protection to avoid crash in fastjet call from pvsorter (81X version)

[arizzi]

same as #14846
this is the 81X version

it addresses
https://hypernews.cern.ch/HyperNews/CMS/get/recoDevelopment/1451/2/1/1/1.html
by adding a protection on "nan" being passed to fastjet.

the nan seems to be coming from ptError and should be further investigated

[cmsbuild]

A new Pull Request was created by @arizzi for CMSSW_8_1_X.

It involves the following packages:

CommonTools/RecoAlgos

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

cms-bot commands are list here #13028

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/13621/console

[cmsbuild]

+1
Tested at: 12cad1f
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-14945/13621/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-14945/13621/summary.html

[cvuosalo]

+1

For #14945 12cad1f

Bug fix to prevent crash due to a NAN in FastJet call from PV sorter. There should be no change in monitored quantities.

#14846 is the 81X version of this PR, and it has already been merged.

The code fix is satisfactory, and Jenkins tests against baseline CMSSW_8_1_X_2016-06-22-1100 show no significant differences, as expected, except for a number of spurious differences in DQM plots related to RPC RecHits.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_1_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar