Fix for Python 2.3 compatibility in `py:with` directive (regression in [240]).
Fix for Python 2.3 compatibility in `py:with` directive (regression in [240]).

mitchellrj/genshi,mitchellrj/genshi,hodgestar/genshi,mitchellrj/genshi,hodgestar/genshi,hodgestar/genshi,mitchellrj/genshi,hodgestar/genshi