CVE-2013-6417: Incomplete fix to CVE-2013-0155 (Unsafe Query Generation Risk)

Due to the way that Rack::Request and Rails::Request interact, it is possible for a 3rd party or custom rack middleware to parse the parameters insecurely and store them in the same key that Rails uses for its own parameters. In the event that happens the application will receive unsafe parameters and could be vulnerable to the earlier vulnerability: it would be possible for an attacker to issue unexpected database queries with IS NULL or empty where clauses.