BUG #7807: "sign" function returns double

The following bug has been logged on the website:

Bug reference:      7807
Logged by:          Andrei Rares
Email address:      a_rares@yahoo.com
PostgreSQL version: 9.1.7
Operating system:   GNU/Linux 3.2.0-35-generic x86_64
Description:        =


In the documentation
(http://www.postgresql.org/docs/9.1/static/functions-math.html) it is
written that the return type is the same as the input, but a query like
'select sign(1::int)' returns a double