WARNING: outfuncs/readfuncs failed to produce an equal rewritten parse tree

Hi

Last time I wrote new tests for session variables.

One is

create variable :"DBNAME".public.var as int;

On platform with enabled WRITE_READ_PARSE_PLAN_TREES I got warning

"WARNING: outfuncs/readfuncs failed to produce an equal rewritten parse
tree"

After some investigation, I found a problem in the RangeVar node.

The field "catalogname" is setted to NULL in _readRangeVar, but it is
compared in _equalRangeVar function.

I thought so it is problem in my patch, but it looks like generic issue:

create table postgres.public.foo(a int);
WARNING: outfuncs/readfuncs failed to produce an equal rewritten parse tree
CREATE TABLE

Is it a known issue?

Regards

Pavel