I wanted to see if there was a bug filed about help icons, so I entered "help icon" in Phabricator's search oval. After about 20 seconds, I get a typical Wikimedia Foundation error page, with details

Request: POST http://phabricator.wikimedia.org/search/, from 10.64.0.172 via cp1044 cp1044 ([10.64.0.172]:80), Varnish XID 1044531748
Forwarded for: 76.14.75.47, 10.64.0.172
Error: 503, Service Unavailable at Mon, 23 Feb 2015 07:36:12 GMT

I retried with "help" and "help asdf" and they all time out with the 503 error, whereas "asdf icon" quickly redirects to the expected Advanced Search form with "No search results." Is "help" a special keyword in Phab search? Entering "help icon" on the advanced search page returns results. So it seems the error occurs in or before the code that turns your search query into a hash and outputs a redirect to https://phabricator.wikimedia.org/search/query/blahblah#R

The POST parameters are

__csrf__=B@l63eniblahblah
__form__=1
query=help foo
search:primary=true