Wikimedia Bugzilla is closed!

I am writing a new result format (for downloading info) and have a trouble with PrintRequest labels.

A query:

{{ #ask: [[Cache:+]]
| mainlabel = -
| ?#        = cache
...
}}

When this request is executed in-place, everything is ok, $field->getPrintRequest()->getLabel() returns "cache" as expected. 

But, if I get a link to a the same query by using

$res->getQueryLink( 'search' )->getURL()

http://.../index.php?title=Special:Ask&x=-5B-5BCache%3A%2B-5D-5D%2F-3F%3Dcache-23-2D&mainlabel=-&...

and follow the link, $field->getPrintRequest()->getLabel() returns "cache#-".

I would expect request should work identically regardless of execution method -- either using #ask parser function or Special:Ask page.