BUG #2542: ALTER USER foo SET bar = func(baz) errors out

The following bug has been logged online:

Bug reference:      2542
Logged by:          David Fetter
Email address:      david@fetter.org
PostgreSQL version: All
Operating system:   All
Description:        ALTER USER foo SET bar = func(baz) errors out
Details:

foo=> ALTER USER foo SET search_path = current_setting('search_path');
ERROR:  syntax error at or near "(" at character 52
LINE 1: ...LTER USER foo SET search_path = current_setting('search_p...

is there some way to let the right hand side of SET be the (TEXT) output of
a function?