TRUNCATE ONLY with foreign keys and triggers disabled

[Dimitrios Apostolou]

Hello list,

While doing TRUNCATE ONLY I get:
  ERROR: cannot truncate a table referenced in a foreign key constraint

But in my case the table to be truncated is already empty, and the 
TRIGGERS are disabled in all tables.

I wonder, is there a deeper reason for this error, or is it just an 
implementation shortcoming? In other words, how easy would it be to write 
a patch that allows TRUNCATE even with foreign keys when triggers are 
disabled or the table is empty?

Thanks in advance,
Dimitris