wierd AND condition evaluation for plpgsql

Hi,

I just noticed plpgsql evaluates all AND'ed conditions even if the first
one fails. Example:
elsif TG_OP = ''UPDATE'' and old.type_reponse = ''abandon''

This will break stuff if the trigger is used on INSERT as
"old.type_reponse" will be substituted and return an error.

Shouldn't plpgsql shortcut AND conditions when a previous one fails, as
perl does?

--    OENONE: Quoi ?   PHEDRE: Je te l'ai prédit, mais tu n'as pas voulu.
(Phèdre,J-B Racine, acte 3, scène 3)