Do not hold on to empty strings passed to getByLabel [9_4]

[Dr15Jones]

When using PyROOT, the string addresses passed to getByLabel are
temporary so we can not hold onto the address even for empty strings.

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for CMSSW_9_4_X.

It involves the following packages:

DataFormats/FWLite

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

cms-bot commands are listed here

• Backported from Do not hold on to empty strings passed to getByLabel #25421

[Dr15Jones]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/31997/console Started: 2018/12/04 23:45

[Dr15Jones]

backport #25421

[Dr15Jones]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_9_4_X IBs after it passes the integration tests and once validation in the development release cycle CMSSW_10_4_X is complete. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @slava77, @smuzaffar, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[cmsbuild]

+1
Tested at: 7f2c51c
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-25420/31997/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-25420/31997/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 27
• DQMHistoTests: Total histograms compared: 2721493
• DQMHistoTests: Total failures: 107
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2721224
• DQMHistoTests: Total skipped: 162
• DQMHistoTests: Total Missing objects: 0

[fabiocos]

+1

it should solve #25416