Failure of test_txn07 in wiredtiger-unit-test

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ERROR: test_txn07.test_txn07.test_ops(none.t1r.trunc-start.var) (subunit.RemotedTestCase)

test_txn07.test_txn07.test_ops(none.t1r.trunc-start.var)

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_StringException: Traceback (most recent call last):

  File "/home/jenkins/jenkins/workspace/wiredtiger-test-unit/test/suite/test_txn07.py", line 164, in test_ops

    c[k] = value

  File "/home/jenkins/jenkins/workspace/wiredtiger-test-unit/lang/python/wiredtiger/__init__.py", line 356, in __setitem__

    if self.insert() != 0:

WiredTigerError: No such file or directory