test_rebalance failing with EBUSY

ERROR: test_rebalance.test_rebalance.test_rebalance(lsm) (subunit.RemotedTestCase)

test_rebalance.test_rebalance.test_rebalance(lsm)

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_StringException: Traceback (most recent call last):

  File "<http://build.wiredtiger.com:8080/job/wiredtiger-test-unit/ws/test/suite/test_rebalance.py",> line 72, in test_rebalance

    self.rebalance(simple_populate, True)

  File "<http://build.wiredtiger.com:8080/job/wiredtiger-test-unit/ws/test/suite/test_rebalance.py",> line 66, in rebalance

    self.session.drop(uri)

WiredTigerError: Device or resource busy