Because fzf processes HTTP GET requests in the main event loop,
accessing the endpoint from within execute/transform actions would
result in a deadlock and hang fzf indefinitely. This commit sets
a 2 second timeout to avoid the deadlock.
The simple success case had only the status line plus a single CRLF,
and pedantic HTTP client implementations (`hyper`) stumbled over
this. A double CRLF makes it OK.
Fixes#3541.
This reverts commit 750b2a6313.
This can cause a deadlock if the endpoints are accessed in the core event
loop via execute action.
fzf --listen 6266 --bind 'space:execute:curl localhost:6266'
Technically, there's no reason to use the API because the information is
already available via `{}` and `{q}`, but I'd like to completely remove
the risk of misuse.