Fix random in TestCSVExportAction

java.lang.AssertionError: Bulk action didn't finish
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.nuxeo.ecm.core.bulk.TestCSVExportAction.testDownloadCSV(TestCSVExportAction.java:227)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$BeforeMethodRunStatement.evaluate(FeaturesRunner.java:285)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$BeforeSetupStatement.evaluate(FeaturesRunner.java:301)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$AfterMethodRunStatement.evaluate(FeaturesRunner.java:332)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$AfterTeardownStatement.evaluate(FeaturesRunner.java:351)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$RulesFactory$1.evaluate(FeaturesRunner.java:429)
	at org.nuxeo.runtime.test.runner.RuntimeDeployment$DeploymentStatement.evaluate(RuntimeDeployment.java:326)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$RulesFactory$1.evaluate(FeaturesRunner.java:429)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)