Ran the builtiin script in JIRA 5.0.7 to rename an existing user's account; the child_name and lower_child_name attributes for the applicable records in the cwd_membership table were not updated to the new value. This prevented the user from logging into JIRA as one of the groups they belonged to was the jira-users (required). The applicable records were deleted from the database manually and I was then able to associate the user with the necessary groups.