If having a multibranch pipeline running a job building a change whose change number is also part of the revision sha1, the job fails with the following stacktrace:
java.lang.IllegalArgumentException: expected one element but was: <com.google.gerrit.extensions.common.ChangeInfo@2f39c0bf, com.google.gerrit.extensions.common.ChangeInfo@f10b960>
at com.google.common.collect.Iterators.getOnlyElement(Iterators.java:312)
at com.google.common.collect.Iterables.getOnlyElement(Iterables.java:268)
at com.urswolfer.gerrit.client.rest.http.changes.ChangeApiRestClient.get(ChangeApiRestClient.java:259)
at com.urswolfer.gerrit.client.rest.http.changes.ChangeApiRestClient.get(ChangeApiRestClient.java:264)
at jenkins.plugins.gerrit.ProjectOpenChanges$1.load(ProjectOpenChanges.java:45)
at jenkins.plugins.gerrit.ProjectOpenChanges$1.load(ProjectOpenChanges.java:43)
at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3568)
at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2350)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2313)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2228)
at com.google.common.cache.LocalCache.get(LocalCache.java:3965)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3969)
at com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4829)
at jenkins.plugins.gerrit.ProjectOpenChanges.get(ProjectOpenChanges.java:56)
at jenkins.plugins.gerrit.AbstractGerritSCMSource.getChangeInfo(AbstractGerritSCMSource.java:87)
at jenkins.plugins.gerrit.GerritEnvironmentContributor.buildEnvironmentFor(GerritEnvironmentContributor.java:82)
at hudson.model.Job.getEnvironment(Job.java:397)
at hudson.model.Run.getEnvironment(Run.java:2273)
at org.jenkinsci.plugins.workflow.job.WorkflowRun.getEnvironment(WorkflowRun.java:425)
at org.jenkinsci.plugins.workflow.support.DefaultStepContext.get(DefaultStepContext.java:65)
at org.jenkinsci.plugins.workflow.steps.StepDescriptor.checkContextAvailability(StepDescriptor.java:259)
at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:206)
at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:153)
at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:108)
at sun.reflect.GeneratedMethodAccessor458.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1218)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1027)
at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157)
at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23)
at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:133)
at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17)
Caused: com.google.common.util.concurrent.UncheckedExecutionException
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2234)
at com.google.common.cache.LocalCache.get(LocalCache.java:3965)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3969)
at com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4829)
at jenkins.plugins.gerrit.ProjectOpenChanges.get(ProjectOpenChanges.java:56)
at jenkins.plugins.gerrit.AbstractGerritSCMSource.getChangeInfo(AbstractGerritSCMSource.java:87)
at jenkins.plugins.gerrit.GerritEnvironmentContributor.buildEnvironmentFor(GerritEnvironmentContributor.java:82)
at hudson.model.Job.getEnvironment(Job.java:397)
at hudson.model.Run.getEnvironment(Run.java:2273)
at org.jenkinsci.plugins.workflow.job.WorkflowRun.getEnvironment(WorkflowRun.java:425)
at org.jenkinsci.plugins.workflow.support.DefaultStepContext.get(DefaultStepContext.java:65)
at org.jenkinsci.plugins.workflow.steps.StepDescriptor.checkContextAvailability(StepDescriptor.java:259)
at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:206)
at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:153)
at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:108)
at sun.reflect.GeneratedMethodAccessor458.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1218)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1027)
at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157)
at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23)
at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:133)
at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:129)
at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17)
at WorkflowScript.run(WorkflowScript:245)
at __cps.transform__(Native Method)
at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:57)
at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:109)
at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:82)
at sun.reflect.GeneratedMethodAccessor72.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
at com.cloudbees.groovy.cps.impl.CollectionLiteralBlock$ContinuationImpl.dispatch(CollectionLiteralBlock.java:55)
at com.cloudbees.groovy.cps.impl.CollectionLiteralBlock$ContinuationImpl.item(CollectionLiteralBlock.java:45)
at sun.reflect.GeneratedMethodAccessor76.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
at com.cloudbees.groovy.cps.impl.ConstantBlock.eval(ConstantBlock.java:21)
at com.cloudbees.groovy.cps.Next.step(Next.java:83)
at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:174)
at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:163)
at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:122)
at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:261)
at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:163)
at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$001(SandboxContinuable.java:19)
at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:35)
at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:32)
at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:108)
at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:32)
at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:174)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:331)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$200(CpsThreadGroup.java:82)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:243)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:231)
at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112)
at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
This happens, because the query for the change info returns multiple results, which isn't expected by the plugin.

This might be related to JENKINS-59958.