Fixed precedence order problem with FormulaEvaluator

[Dr15Jones]

Under certain conditions one of the evaluation nodes could be dropped because of a faulty precedence handling.
Unit tests were also extended to test this case.

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for CMSSW_8_0_X.

It involves the following packages:

CommonTools/Utils

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

cms-bot commands are listed here #13028

[Dr15Jones]

please test

[Dr15Jones]

backport #16733

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/16563/console

[cmsbuild]

+1
Tested at: 8cabd8f
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16736/16563/summary.html

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:
d4cb14f
e4ca442
9e1ccc1
You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16736/16563/git-log-recent-commits
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16736/16563/git-merge-result

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16736/16563/summary.html

[slava77]

+1

for #16736 8cabd8f

• fix to formula in JEC not yet released for standard workflows.
• jenkins tests pass and comparisons show no differences

The new JEC will be used for analyses in 80X. This fix is needed in 80X.