ecpg preprocessor regression in 9.0

This used to work in the PostgreSQL 8.4 ecpg preprocessor:

EXEC SQL EXECUTE mystmt USING 1.23;

but in 9.0 it throws an error:

floattest.pgc:39: ERROR: variable "1" is not declared

Attached is the full test case, drop it in
src/interfaces/ecpg/test/preproc and compile.

I bisected the cause to this commit:

commit b2bddc2ff22f0c3d54671e43c67a2563deed7908
Author: Michael Meskes <meskes@postgresql.org>
Date:   Thu Apr 1 08:41:01 2010 +0000

     Applied Zoltan's patch to make ecpg spit out warnings if a local
variable hides a global one with the same name.

I don't immediately see why that's causing it, but it doesn't seem
intentional.

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com