dblink versus long connection strings

This bug report:
http://archives.postgresql.org/pgsql-bugs/2010-11/msg00139.php
shows that this patch was ill-considered:
http://archives.postgresql.org/pgsql-committers/2010-06/msg00013.php
and this later attempt didn't fix it, because it still misbehaves in
HEAD:
http://archives.postgresql.org/pgsql-committers/2010-06/msg00070.php
not to mention that that second patch didn't even touch pre-8.4
branches.

I'm inclined to think that we should just change all the
truncate_identifier calls to warn=false, and forget about providing
identifier-truncated warnings here.  It's too difficult to tell whether
a string is really meant as an identifier.
        regards, tom lane