SCM trigger warnings were caused by a misconfigured job on Staging. GitHub warnings are still there but they're not something new. New core installed.

Checking the logs - there's still a lot of warnings as reported in combined with SCM trigger warnings:

Apr 03, 2017 1:36:42 PM com.cloudbees.jenkins.GitHubRepositoryName create
WARNING: Could not match URL https://gerrit.ovirt.org/jenkins
Apr 03, 2017 1:36:42 PM jenkins.triggers.SCMTriggerItem$SCMTriggerItems resolveMultiScmIfConfigured
WARNING: null
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor266.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at jenkins.triggers.SCMTriggerItem$SCMTriggerItems.resolveMultiScmIfConfigured(SCMTriggerItem.java:143)
at hudson.model.Project.getSCMs(Project.java:121)
at com.cloudbees.jenkins.GitHubRepositoryNameContributor$FromSCM.parseAssociatedNames(GitHubRepositoryNameContributor.java:106)
at com.cloudbees.jenkins.GitHubRepositoryNameContributor.parseAssociatedNames(GitHubRepositoryNameContributor.java:91)
at org.jenkinsci.plugins.github.util.JobInfoHelpers$3.apply(JobInfoHelpers.java:63)
at org.jenkinsci.plugins.github.util.JobInfoHelpers$3.apply(JobInfoHelpers.java:61)
at com.google.common.collect.Iterators$8.next(Iterators.java:812)
at com.google.common.collect.Iterables$3.next(Iterables.java:508)
at com.google.common.collect.Iterables$3.next(Iterables.java:501)
at com.google.common.collect.Iterators$5.hasNext(Iterators.java:544)
at com.google.common.collect.Lists.newArrayList(Lists.java:138)
at com.google.common.collect.Lists.newArrayList(Lists.java:119)
at org.jenkinsci.plugins.github.util.FluentIterableWrapper.toList(FluentIterableWrapper.java:137)
at com.cloudbees.jenkins.Cleaner.doRun(Cleaner.java:67)
at hudson.triggers.SafeTimerTask.run(SafeTimerTask.java:50)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at org.jenkinsci.plugins.multiplescms.MultiSCM.getConfiguredSCMs(MultiSCM.java:54)
... 25 more

Apr 03, 2017 1:36:42 PM com.cloudbees.jenkins.GitHubRepositoryName create
WARNING: Could not match URL git://gerrit.ovirt.org/ovirt-engine.git

Patch submitted for review

Jenkins 2.46.1 installed on Staging and tested successfully, including Gerrit integration.