I know I've seen test_obj.py:TestS3ApiObj.test_object_PUT_copy_metadata_copy
fail in the gate on occassion; testing locally, I saw it fail twice out
of 5,000 attempts, but I suspect the prevalence is higher in the more
resource-constrained gate.
With this change, I saw no failures through 15,000 attempts.
Change-Id: I7c3cd4fecf5c8db355cc07f18a07d27962309b9b