BUG #12046: lower_inf('(-infinity,today)'::tsrange) returns false

The following bug has been logged on the website:

Bug reference: 12046
Logged by: Nathan Cutler
Email address: presnypreklad(at)gmail(dot)com
PostgreSQL version: 9.3.5
Operating system: openSUSE 13.2
Description:

In the course of writing a program that accepts tsrange literals from the
user, which are then plugged into various SQL queries, today I was testing
some tsranges to see how they are interpreted by PostgreSQL 9.3.5.

This one, in particular, behaves strangely: '(-infinity,today)'::tsrange

The lower_inf function says the lower bound is not infinite (!)

test=> SELECT lower_inf('(-infinity,today)'::tsrange);
lower_inf
-----------
f
(1 row)

Yet PostgreSQL reports that this tsrange contains a timestamp like
'1000-01-01 BC' . . .

test=> SELECT '(-infinity,today)'::tsrange @> '1000-01-01 BC'::timestamp;
?column?
----------
t
(1 row)

Seems like a bug?