BUG #7867: Similarity function fails

The following bug has been logged on the website:

Bug reference:      7867
Logged by:          Michele Baravalle
Email address:      michele.baravalle@me.com
PostgreSQL version: 9.2.3
Operating system:   Mac OSX 10.8
Description:        =


Using this sql:

SELECT similarity('=D0=9A=D1=80=D1=83=D0=B8=D0=B7-=D0=BA=D0=BE=D0=BD=D1=82=
=D1=80=D0=BE=D0=BB=D1=8C =D0=BE=D1=82=D0=BA=D0=BB=D1=8E=D1=87=D0=B5=D0=BD',=
 '=D0=9A=D1=80=D1=83=D0=B8=D0=B7-=D0=BA=D0=BE=D0=BD=D1=82=D1=80=D0=BE=D0=BB=
=D1=8C =D0=BE=D1=82=D0=BA=D0=BB=D1=8E=D1=87=D0=B5=D0=BD');

work well on Linux and Windows and the result is 1: on OSX the result is
NaN.

Thanks