Upstream task: https://secure.phabricator.com/T4475
I. Observed: I'm directed to https://phabricator.wikimedia.org/search/query/c3Suo_oyO3VI/#R
II. Expected: I'm directed to a search related to what I'm using and doing, i.e. maniphest (https://phabricator.wikimedia.org/maniphest/query/advanced/ )
Though well intentioned, I don't think this is a good idea. At least I hope this would not mean that I can't type ahead users or projects in the search bar anymore when I'm in a task...
Even in MediaWiki search, autocompletion, "go" search and full text search are completely different. Autocompletion and redirect can continue to be phabricator-wide, while full text searches go to the specific "namespace" (application) in question.
Check https://secure.phabricator.com/D12509 the see the implementation of a selector for the scope of the search, which basically solved the problem described here.
Fixed a while ago by the scope selector implementation for the global search: Click the Globe (=global search) dropdown in front of the search text field and set ""Search Current Application"".
Changing the search scope depending on what kind of item you're looking at won't be supported (and feels confusing enough).