tstzrange with ... 'infinity'] + upper_inf() using 9.2.4

Hi,

> select upper_inf(tsrange('2013-05-01'::timestamp, 'infinity'::timestamp, '[]'));
 upper_inf
-----------
 f
(1 row)

As far as I understood the docs, this query should return true, as the upper bound includes 'infinity'?

[http://www.postgresql.org/docs/9.2/interactive/functions-range.html]
"The lower and upper functions return null if the range is empty or the requested bound is infinite. The lower_inc,
upper_inc,lower_inf, and upper_inf functions all return false for an empty range." 

[http://www.postgresql.org/docs/9.2/interactive/rangetypes.html]
"Also, some element types have a notion of "infinity", but that is just another value so far as the range type
mechanismsare concerned. For example, in timestamp ranges, [today,] means the same thing as [today,). But
[today,infinity]means something different from [today,infinity) — the latter excludes the special timestamp value
infinity.
The functions lower_inf and upper_inf test for infinite lower and upper bounds of a range, respectively."


Regards
Ralph