[web2py] dal connection failed on legacy postgres db

[Oleg Butovich]

subj. with error:
RuntimeError: unrecognized configuration parameter "standard_conforming_strings"
 (tried 5 times)

I propose set standard_conforming_strings only if it defined.. :)

See attached patch

# HG changeset patch
# User oleg
# Date 1285795123 -7200
# Node ID 9de0c834114345fdac603f05d0a685eb4e7d6ab7
# Parent  ba367ac7862c336457bbb04faf34eb4ea2d6b4eb
fix for legacy postgresql without standard_conforming_strings parameter

diff -r ba367ac7862c -r 9de0c8341143 gluon/sql.py
--- a/gluon/sql.py	Mi Sep 29 09:16:34 2010 -0500
+++ b/gluon/sql.py	Mi Sep 29 23:18:43 2010 +0200
@@ -1017,7 +1017,8 @@
             self['_lastsql'] = query
             self._execute(query)
             self._execute("SET CLIENT_ENCODING TO 'UNICODE';")  # ## not completely sure but should work
-            self._execute("SET standard_conforming_strings=on;")
+            if self._connection.get_parameter_status('standard_conforming_strings'):
+                self._execute("SET standard_conforming_strings=on;")
         elif self._uri.startswith('oracle://'):
             self._dbname = 'oracle'
             self._pool_connection(lambda : \