CTPPS: empty alignment fix

[grzanka]

Fixes a bug which resulted in empty alignment being returned.

[cmsbuild]

A new Pull Request was created by @grzanka (Leszek Grzanka) for CMSSW_8_1_X.

It involves the following packages:

Geometry/VeryForwardGeometryBuilder

@civanch, @Dr15Jones, @ianna, @mdhildreth, @cmsbuild, @davidlange6 can you please review it and eventually sign? Thanks.
@ghellwig this is something you requested to watch as well.
@slava77, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[grzanka]

@slava77 could you please take a look ? Once it is merged I will backport it to 80X.

[slava77]

@cmsbuild please test

@grzanka I'm not sure what I should be checking
cmsbuild tests should show if code runs OK (if it's supposed to be running in the 2016B workflow, where we are using a run with CTPPS included)

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/14857/console

[cmsbuild]

+1
Tested at: 665da60
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-15675/14857/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-15675/14857/summary.html

[ianna]

+1

[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, @smuzaffar

[davidlange6]

+1