Error synching task list from Eclipse

I originally filed https://bugs.eclipse.org/bugs/show_bug.cgi?id=421297 with Eclipse. They closed it, pointing out that the stack trace included "com.atlassian.jira.rest.client" and told me to file this with Atlassian. From the product list, I don't see anything closer than JIRA. I'm just repeating the same report here, with some additional information.

I have a Kepler workspace that I've been using for a while. I've had the JIRA connector installed and running for a long time.

Today was the first time I created some projects from a cloned git workspace. Sometime after the first project was created, I started to get error dialogs popping up every few minutes saying 'An internal error occurred during "Synchronizing Task List".' This continued to happen while I had those git projects in my workspace. After several hours of this, the error dialog popping up every synch interval, I then deleted all of the git projects. I don't know if that's exactly what's causing the conflict, but now there are no more error dialogs. I'm going to be checking out those projects again in the next few days.

This is the stack trace from the log:

!ENTRY org.eclipse.core.jobs 4 2 2013-11-07 18:06:17.475
!MESSAGE An internal error occurred during: "Synchronizing Task List".
!STACK 0
com.sun.jersey.spi.service.ServiceConfigurationError: com.sun.jersey.spi.HeaderDelegateProvider: The class com.sun.jersey.core.impl.provider.header.LocaleProvider implementing provider interface com.sun.jersey.spi.HeaderDelegateProvider could not be instantiated: Cannot cast com.sun.jersey.core.impl.provider.header.LocaleProvider to com.sun.jersey.spi.HeaderDelegateProvider
at com.sun.jersey.spi.service.ServiceFinder.fail(ServiceFinder.java:602)
at com.sun.jersey.spi.service.ServiceFinder.access$800(ServiceFinder.java:159)
at com.sun.jersey.spi.service.ServiceFinder$LazyObjectIterator.hasNext(ServiceFinder.java:892)
at com.sun.jersey.core.spi.factory.AbstractRuntimeDelegate.<init>(AbstractRuntimeDelegate.java:76)
at com.sun.ws.rs.ext.RuntimeDelegateImpl.<init>(RuntimeDelegateImpl.java:56)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at java.lang.Class.newInstance(Class.java:374)
at javax.ws.rs.ext.FactoryFinder.newInstance(FactoryFinder.java:65)
at javax.ws.rs.ext.FactoryFinder.find(FactoryFinder.java:155)
at javax.ws.rs.ext.RuntimeDelegate.findDelegate(RuntimeDelegate.java:105)
at javax.ws.rs.ext.RuntimeDelegate.getInstance(RuntimeDelegate.java:91)
at javax.ws.rs.core.UriBuilder.newInstance(UriBuilder.java:69)
at javax.ws.rs.core.UriBuilder.fromUri(UriBuilder.java:80)
at com.atlassian.jira.rest.client.internal.jersey.JerseyJiraRestClient.<init>(JerseyJiraRestClient.java:64)
at com.atlassian.jira.rest.client.internal.jersey.JerseyJiraRestClientFactory.create(JerseyJiraRestClientFactory.java:39)
at com.atlassian.connector.eclipse.internal.jira.core.service.rest.JiraRestClientAdapter.<init>(JiraRestClientAdapter.java:159)
at com.atlassian.connector.eclipse.internal.jira.core.service.JiraClient.createRestClient(JiraClient.java:179)
at com.atlassian.connector.eclipse.internal.jira.core.service.JiraClient.getRestClient(JiraClient.java:154)
at com.atlassian.connector.eclipse.internal.jira.core.service.JiraClient.getServerInfo(JiraClient.java:627)
at com.atlassian.connector.eclipse.internal.jira.core.service.JiraClientCache.refreshServerInfo(JiraClientCache.java:321)
at com.atlassian.connector.eclipse.internal.jira.core.service.JiraClientCache.refreshDetails(JiraClientCache.java:288)
at com.atlassian.connector.eclipse.internal.jira.core.JiraRepositoryConnector.performQuery(JiraRepositoryConnector.java:125)
at org.eclipse.mylyn.internal.tasks.core.sync.SynchronizeQueriesJob.synchronizeQuery(SynchronizeQueriesJob.java:311)
at org.eclipse.mylyn.internal.tasks.core.sync.SynchronizeQueriesJob.synchronizeQueries(SynchronizeQueriesJob.java:268)
at org.eclipse.mylyn.internal.tasks.core.sync.SynchronizeQueriesJob.run(SynchronizeQueriesJob.java:201)
at org.eclipse.mylyn.internal.tasks.core.sync.SynchronizeRepositoriesJob.updateQueries(SynchronizeRepositoriesJob.java:186)
at org.eclipse.mylyn.internal.tasks.core.sync.SynchronizeRepositoriesJob.run(SynchronizeRepositoriesJob.java:142)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
Caused by: java.lang.ClassCastException: Cannot cast com.sun.jersey.core.impl.provider.header.LocaleProvider to com.sun.jersey.spi.HeaderDelegateProvider
at java.lang.Class.cast(Class.java:3084)
at com.sun.jersey.spi.service.ServiceFinder$LazyObjectIterator.hasNext(ServiceFinder.java:851)
... 28 more