Fix random TestMailTreeHelper failure on nuxeo-cmf

Error Message

Concurrency Error: Session was started in thread 24 (Nuxeo-Work-fulltextUpdater-1) but is being used in thread 1 (main)

Stacktrace

java.lang.IllegalStateException: Concurrency Error: Session was started in thread 24 (Nuxeo-Work-fulltextUpdater-1) but is being used in thread 1 (main)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.checkThread(SessionImpl.java:227)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.checkLive(SessionImpl.java:177)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.closeSession(SessionImpl.java:271)
	at org.nuxeo.ecm.core.storage.sql.RepositoryImpl.closeAllSessions(RepositoryImpl.java:431)
	at org.nuxeo.ecm.core.storage.sql.RepositoryImpl.close(RepositoryImpl.java:411)
	at org.nuxeo.ecm.core.storage.sql.ra.ManagedConnectionFactoryImpl.shutdown(ManagedConnectionFactoryImpl.java:298)
	at org.nuxeo.ecm.core.storage.sql.ra.ConnectionFactoryImpl.shutdown(ConnectionFactoryImpl.java:191)
	at org.nuxeo.ecm.core.repository.RepositoryService.shutdown(RepositoryService.java:56)
	at org.nuxeo.ecm.core.repository.RepositoryService$1.handleEvent(RepositoryService.java:77)
	at org.nuxeo.runtime.api.Framework.sendEvent(Framework.java:313)
	at org.nuxeo.runtime.AbstractRuntimeService.stop(AbstractRuntimeService.java:142)
	at org.nuxeo.runtime.api.Framework.shutdown(Framework.java:173)
	at org.nuxeo.runtime.test.NXRuntimeTestCase.wipeRuntime(NXRuntimeTestCase.java:363)
	at org.nuxeo.runtime.test.NXRuntimeTestCase.tearDown(NXRuntimeTestCase.java:191)
	at org.nuxeo.ecm.core.storage.sql.SQLRepositoryTestCase.tearDown(SQLRepositoryTestCase.java:91)
	at org.nuxeo.ecm.core.storage.sql.TXSQLRepositoryTestCase.tearDown(TXSQLRepositoryTestCase.java:77)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:37)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
	at org.nuxeo.runtime.test.runner.FeaturesRunner.runChild(FeaturesRunner.java:401)
	at org.nuxeo.runtime.test.runner.FeaturesRunner.runChild(FeaturesRunner.java:55)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
	at org.nuxeo.runtime.test.runner.FeaturesRunner.run(FeaturesRunner.java:366)
	at org.junit.runners.Suite.runChild(Suite.java:128)
	at org.junit.runners.Suite.runChild(Suite.java:24)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:136)
	at org.apache.maven.surefire.junitcore.JUnitCoreWrapper.createRequestAndRun(JUnitCoreWrapper.java:113)
	at org.apache.maven.surefire.junitcore.JUnitCoreWrapper.executeEager(JUnitCoreWrapper.java:85)
	at org.apache.maven.surefire.junitcore.JUnitCoreWrapper.execute(JUnitCoreWrapper.java:54)
	at org.apache.maven.surefire.junitcore.JUnitCoreProvider.invoke(JUnitCoreProvider.java:134)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)

Standard Output

04:22:35,425 WARN  [TransactionalCoreSessionWrapper] CoreSession.isStateSharedByAllThreadSessions invoked without a transaction, check debug logs for more information
04:22:35,552 ERROR [OSGiRuntimeService] Nuxeo EP Started
======================================================================
= Component Loading Status: Pending: 6 / Unstarted: 0 / Total: 131
  * service:org.nuxeo.ecm.platform.notification.document.routing.NotificationContrib requires [service:org.nuxeo.ecm.platform.notification.service.NotificationContrib]
  * service:org.nuxeo.ecm.classification.audit requires [service:org.nuxeo.ecm.platform.audit.service.NXAuditEventsService]
  * service:org.nuxeo.ecm.directory.sql.test requires [service:org.nuxeo.ecm.directory.sql.SQLDirectoryFactory]
  * service:org.nuxeo.ecm.platform.webapp.core.ExceptionHandlingContrib requires [service:org.nuxeo.ecm.platform.web.common.exceptionhandling.service.ExceptionHandlingContrib]
  * service:org.nuxeo.theme.nuxeo.default requires [service:org.nuxeo.theme.fragments, service:org.nuxeo.theme.core, service:org.nuxeo.theme.html, service:org.nuxeo.theme.jsf]
  * service:org.nuxeo.ecm.platform.ui.web.SeamRemotingJSBuilderComponent.coreContrib requires [service:org.nuxeo.ecm.platform.ui.web.SeamRemotingJSBuilderComponent]
======================================================================