python - be: Use getattro instead of getattr.

Log Message:
-----------
Use getattro instead of getattr.

Fixes bug where attributes are not fetched properly. ie, Transaction.__call__
was failing because the generic getattr was not being called.

Modified Files:
--------------
    be/src:
        xact.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/xact.c.diff?r1=1.2&r2=1.3)