memcached return oom error on set right after startup

This showed up during a smoke test run. Will look into reproducing it.

Starting test: Test expiration operations.
Running sequence on ['10.1.5.80', '8091', '11211', '11210']
Running sequence on ['10.1.5.77', '8091', '11211', '11210']
Running sequence on ['10.1.5.78', '8091', '11211', '11210']
Running sequence on ['10.1.5.79', '8091', '11211', '11210']
Running sequence on ['10.1.4.121', '8091', '11211', '11210']
Running sequence on ['10.1.2.202', '8091', '11211', '11210']
Traceback (most recent call last):
File "tests/expiry/run", line 49, in ?
store(mc, 'a1')
File "tests/expiry/run", line 25, in store
mc.set(k, EXPIRY, 0, k)
File "/tmp/testrunner/lib/mc_bin_client.py", line 124, in set
return self._mutate(memcacheConstants.CMD_SET, key, exp, flags, 0, val)
File "/tmp/testrunner/lib/mc_bin_client.py", line 98, in _mutate
cas)
File "/tmp/testrunner/lib/mc_bin_client.py", line 94, in _doCmd
return self._handleSingleResponse(opaque)
File "/tmp/testrunner/lib/mc_bin_client.py", line 87, in _handleSingleResponse
cmd, opaque, cas, keylen, extralen, data = self._handleKeyedResponse(myopaque)
File "/tmp/testrunner/lib/mc_bin_client.py", line 83, in _handleKeyedResponse
raise MemcachedError(errcode, rv)
mc_bin_client.MemcachedError: Memcached error #130: Out of memory
Elapsed time (s): 20
FAIL : Test expiration operations.