Fix logic issue in psycopg2 instrumentation related to register_type.
Fix logic issue in psycopg2 instrumentation related to register_type.

dirtycoder/opbeat_python,tarkatronic/opbeat_python,beniwohli/apm-agent-python,daikeren/opbeat_python,beniwohli/apm-agent-python,beniwohli/apm-agent-python,daikeren/opbeat_python,ticosax/opbeat_python,patrys/opbeat_python,tarkatronic/opbeat_python,ticosax/opbeat_python,daikeren/opbeat_python,patrys/opbeat_python,patrys/opbeat_python,dirtycoder/opbeat_python,ticosax/opbeat_python,dirtycoder/opbeat_python,tarkatronic/opbeat_python,patrys/opbeat_python,beniwohli/apm-agent-python