BUG #8679: Error in regex function

The following bug has been logged on the website:

Bug reference: 8679
Logged by: Andrzej
Email address: spmpro(at)pochta(dot)ru
PostgreSQL version: 9.2.0
Operating system: Ubuntu
Description:

Hi, I make command select regexp_replace('rewqe ','(?<=[q]{1})[e]{1}(?=[\-
$]+)','11');
and he return error 'invalid regular expression: quantifier operand
invalid', but regex is correct (check by http://gskinner.com/RegExr/) This
error repeat in another regex function (regexp_matches,
regexp_split_to_array).

But command select regexp_replace('rewqe ','[e]{1}(?=[\- $]+)','11') work
good. May be, regex construction (?<=\pattern\) is not support?