Protect against missing PixelClusters

[Martin-Grunewald]

Protect against missing PixelClusters EDProduct;
done is the same way as in the already-existing protection against missing StripClusters.

[cmsbuild]

A new Pull Request was created by @Martin-Grunewald (Martin Grunewald) for CMSSW_7_2_X.

Protect against missing PixelClusters

It involves the following packages:

SimTracker/TrackerHitAssociation

@cmsbuild, @civanch, @Degano, @mdhildreth, @nclopezo can you please review it and eventually sign? Thanks.
@threus, @GiacomoSguazzoni, @cerati, @rovere, @venturia this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
You can reject by replying to this message having '-1' in the first line of your reply.

[Martin-Grunewald]

The file-diff is spuriously large as the indentation of the code block encapsulated in
the body of the added if-statement has of course changed...

[ktf]

For a cleaned up version please use:

https://github.com/cms-sw/cmssw/pull/4365/files?w=1

[cmsbuild]

+1
Tested at: 5317cac
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-4365/178/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-4365/178/summary.html

[Martin-Grunewald]

PING PING PING to simulation - please sign!

[civanch]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_2_X IBs unless changes (tests are also fine).