BUG #13513: Turning a table into a view

The following bug has been logged on the website:

Bug reference:      13513
Logged by:          Piergiorgio Buongiovanni
Email address:      p.buongiovanni@net-international.com
PostgreSQL version: 9.2.13
Operating system:   Centos 6.4 (Final)
Description:

I create the table MyTable with a foreign key. In a second time I drop that
foreign key (using ALTER TABLE command) in order to turn the table MyTable
into a view, using the command: CREATE RULE "_RETURN" AS ON SELECT TO
MyTable DO INSTEAD...
The server doesn't allow me to esecute this command as it tells me that
there is a foreign key or a trigger on the table MyTable.
The problem does not occur if I create the table MyTable without foreign
keys at the beginnning.