I"m not sure I understand. You first said that the bug is on regular PostgreSQL (and I can't reproduce it on 9.0 regular PostgreSQL). When you explain the bug and if I read correctly your patch, it fixes EDB database only.
So is it a fix for EDB databases or PostgreSQL databases?
Well, the SQL does get fired against a PG database in the EDBAS mode for me. I too was puzzled about the minimum version check being EDBAS specific.
Anyways the fix to compare a char to a char should be there in any case..