Description of problem:
Encountered this runtime error against stage candlepin during an automated test run.

Version-Release number of selected component (if applicable):
  subscription.rhn.stage.redhat.com
  subscription management server: 0.9.51.15-1

How reproducible:
  is not easy to reproducible

Steps to Reproduce:
Pasting from a test automation log...
2016-09-08 06:15:07.029  FINE: ssh root.eng.rdu.redhat.com subscription-manager subscribe --pool=8a99f9815582f734015585f9989d5047
2016-09-08 06:16:08.858  FINE: Stdout: 
2016-09-08 06:16:08.858  FINE: Stderr: Runtime Error could not obtain pessimistic lock at com.mysql.jdbc.SQLError.createSQLException:1,078

2016-09-08 06:16:08.859  FINE: ExitCode: 70
2016-09-08 06:16:08.859  FINE: ssh root.eng.rdu.redhat.com LINE_NUMBER=$(grep --line-number 'Making request:' /var/log/rhsm/rhsm.log | tail --lines=1 | cut --delimiter=':' --field=1); if [ -n "$LINE_NUMBER" ]; then tail -n +$LINE_NUMBER /var/log/rhsm/rhsm.log; fi;
2016-09-08 06:16:08.957  WARNING: Last request from /var/log/rhsm/rhsm.log:
2016-09-08 06:15:20,797 [DEBUG] subscription-manager:30381:MainThread @connection.py:573 - Making request: POST /subscription/consumers/25f1a0fb-59cf-48aa-a089-897a01282502/entitlements?pool=8a99f9815582f734015585f9989d5047
2016-09-08 06:16:12,079 [DEBUG] subscription-manager:30381:MainThread @connection.py:602 - Response: status=500
2016-09-08 06:16:12,080 [ERROR] subscription-manager:30381:MainThread @managercli.py:1570 - Runtime Error could not obtain pessimistic lock at com.mysql.jdbc.SQLError.createSQLException:1,078
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/subscription_manager/managercli.py", line 1560, in _do_command
    ents = self.cp.bindByEntitlementPool(self.identity.uuid, pool, self.options.quantity)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 1169, in bindByEntitlementPool
    return self.conn.request_post(method)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 697, in request_post
    return self._request("POST", method, params)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 611, in _request
    self.validateResponse(result, request_type, handler)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 661, in validateResponse
    raise RestlibException(response['status'], error_msg, response.get('headers'))
RestlibException: Runtime Error could not obtain pessimistic lock at com.mysql.jdbc.SQLError.createSQLException:1,078


Actual results:
  above

Expected results:


Additional info: