plpythonu: how to catch plpy.execute() exceptions

Hello all,

I am trying to create a plpythonu function that will execute some SQLs
stored in a table (because it should work much faster than executing
from remote).

The thing is that I cannot catch the exception raised by plpy.execute().

I tried this with the following code:

CREATE OR REPLACE FUNCTION __syncpg_execute() RETURNS boolean
AS $$
try:
plpy.execute("SELECT * FROM not_existing_table", 5)
except Exception, exc:
plpy.notice("Exception %s" % str(exc) )
return True
$$ LANGUAGE plpythonu;

The result is:
# select __syncpg_execute();
WARNING: PL/Python: plpy.SPIError: unrecognized error in PLy_spi_execute_query
CONTEXT: PL/Python function "__syncpg_execute"
NOTICE: Exception error return without exception set
CONTEXT: PL/Python function "__syncpg_execute"
ERROR: relation "not_existing_table" does not exist
LINE 1: SELECT * FROM not_existing_table
^
QUERY: SELECT * FROM not_existing_table
CONTEXT: PL/Python function "__syncpg_execute"

I am using Postgresql9.0 with python 2.4.3

Thank you

--
Best regards,
Dragos Moinescu