Set/Increment/Decrement value operations failed with MemcachedError: Memcached error #132 'Internal error'

MemcachedError: Memcached error #132 'Internal error' occured during some Set/Increment/Decrement operations on membase bucket.

[Tests Failed]
test_set_pos_float_value_pos_flag_key_never_expired
test_incr_with_exist_key_decr_then_incr_never_expired
test_decr_with_exist_key_incr_then_decr_never_expired

Jenkins Job link:
http://qa.sc.couchbase.com/job/CouchbaseServer-SanityTest-4Nodes-Centos64-openssl_1/230/consoleFull

[Test Ran]
./testrunner -i fournode.ini get-cbcollect-info=True -t memcapable.SimpleSetMembaseBucketDefaultPort.test_set_pos_float_value_pos_flag_key_never_expired

[2014-01-21 23:34:52,823] - [data_helper:331] INFO - creating proxy client 172.23.105.131:11211 default
ERROR

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ERROR: test_set_pos_float_value_pos_flag_key_never_expired (memcapable.SimpleSetMembaseBucketDefaultPort)
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Traceback (most recent call last):
File "pytests/memcapable.py", line 154, in test_set_pos_float_value_pos_flag_key_never_expired
self.memcapableTestBase.set_test(key_test, exp_time, flagsList, valuesList)
File "pytests/memcapable.py", line 65, in set_test
client.set(key, exp, f, v)
File "lib/mc_bin_client.py", line 163, in set
return self._mutate(memcacheConstants.CMD_SET, key, exp, flags, 0, val)
File "lib/mc_bin_client.py", line 132, in _mutate
cas)
File "lib/mc_bin_client.py", line 128, in _doCmd
return self._handleSingleResponse(opaque)
File "lib/mc_bin_client.py", line 121, in _handleSingleResponse
cmd, opaque, cas, keylen, extralen, data = self._handleKeyedResponse(myopaque)
File "lib/mc_bin_client.py", line 117, in _handleKeyedResponse
raise MemcachedError(errcode, rv)
MemcachedError: Memcached error #132 'Internal error': Internal error for vbucket :592 to mc 172.23.105.131:11211

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./testrunner -i fournode.ini get-cbcollect-info=True -t memcapable.SimpleIncrMembaseBucketDefaultPort.test_incr_with_exist_key_decr_then_incr_never_expired
======================================================================
ERROR: test_incr_with_exist_key_decr_then_incr_never_expired (memcapable.SimpleIncrMembaseBucketDefaultPort)
----------------------------------------------------------------------
Traceback (most recent call last):
File "pytests/memcapable.py", line 221, in test_incr_with_exist_key_decr_then_incr_never_expired
update_v = self.memcapableTestBase.incr_test(key_test, exp_time, 0, value, incr_amt, decr_amt, incr_time)
File "pytests/memcapable.py", line 87, in incr_test
client.set(key, exp, flags, value)
File "lib/mc_bin_client.py", line 163, in set
return self._mutate(memcacheConstants.CMD_SET, key, exp, flags, 0, val)
File "lib/mc_bin_client.py", line 132, in _mutate
cas)
File "lib/mc_bin_client.py", line 128, in _doCmd
return self._handleSingleResponse(opaque)
File "lib/mc_bin_client.py", line 121, in _handleSingleResponse
cmd, opaque, cas, keylen, extralen, data = self._handleKeyedResponse(myopaque)
File "lib/mc_bin_client.py", line 117, in _handleKeyedResponse
raise MemcachedError(errcode, rv)
MemcachedError: Memcached error #132 'Internal error': Internal error for vbucket :592 to mc 172.23.105.131:11211

----------------------------------------------------------------------

./testrunner -i fournode.ini get-cbcollect-info=True -t memcapable.SimpleDecrMembaseBucketDefaultPort.test_decr_with_exist_key_incr_then_decr_never_expired

======================================================================
ERROR: test_decr_with_exist_key_incr_then_decr_never_expired (memcapable.SimpleDecrMembaseBucketDefaultPort)
----------------------------------------------------------------------
Traceback (most recent call last):
File "pytests/memcapable.py", line 624, in test_decr_with_exist_key_incr_then_decr_never_expired
update_v = self.memcapableTestBase.decr_test(key_test, exp_time, 0, value, incr_amt, decr_amt, decr_time)
File "pytests/memcapable.py", line 111, in decr_test
client.set(key, exp, flags, value)
File "lib/mc_bin_client.py", line 163, in set
return self._mutate(memcacheConstants.CMD_SET, key, exp, flags, 0, val)
File "lib/mc_bin_client.py", line 132, in _mutate
cas)
File "lib/mc_bin_client.py", line 128, in _doCmd
return self._handleSingleResponse(opaque)
File "lib/mc_bin_client.py", line 121, in _handleSingleResponse
cmd, opaque, cas, keylen, extralen, data = self._handleKeyedResponse(myopaque)
File "lib/mc_bin_client.py", line 117, in _handleKeyedResponse
raise MemcachedError(errcode, rv)
MemcachedError: Memcached error #132 'Internal error': Internal error for vbucket :592 to mc 172.23.105.131:11211

----------------------------------------------------------------------