This reverts commit 29b66ff0ec.
Rationale:
1) It's not a security feature (abuse of prefetch can be on any server it's not
more/less risky on localhost), it's pseudo-security measure
2) It's not to us to judge if it has no use-case (in fact it has, ex: two dev
speaking and experimenting about urls of their local site/app instance,
local web apps...)
refs #388