UPR streams getting stuck

When I run the following test with 1024 vbuckets, the view engine log says that it is waiting for mutations from ep-engine indefinitely.

$ NODES=1 TEST=view.viewquerytests.ViewQueryTests.test_employee_dataset_startkey_endkey_queries_rebalance_in,num_nodes_to_add=1,skip_rebalance=true,docs-per-day=1 make any-test

[couchdb:error,2014-05-29T15:10:36.205,n_0@127.0.0.1:<0.898.0>:couch_log:error:42]upr client (<0.898.0>): Obtaining mutation from server timed out after 60.0 seconds [RequestId 9818 PartId 299]. Waiting...
[couchdb:error,2014-05-29T15:10:36.283,n_0@127.0.0.1:<0.778.0>:couch_log:error:42]upr client (<0.778.0>): Obtaining mutation from server timed out after 60.0 seconds [RequestId 12080 PartId 406]. Waiting...

I tried checking out an older ep-engine commit, 86b88cd6e90baf6dafbabffa1ba7bc42379cc5b2 and I do not see upr streams getting stuck.