[MERGE][ping] Better connection sharing for pycurl

[Vincent Ladeuil]

>>>>> "Andrew" == Andrew Bennetts <andrew at canonical.com> writes:

<snip/>

    Andrew> Just to second this, changing it to only happen for
    Andrew> POSTs is fine with me.  

Thanks.

    Andrew> I didn't do that originally just out of
    Andrew> laziness/simplicity.

Sure.

    Andrew> If it's now as simple to only do it for POSTs, then
    Andrew> that's fine.

Ok.

    Andrew> (Disabling the Expect header means that pycurl
    Andrew> doesn't wait for 1 second when POSTing, which is an
    Andrew> obvious performance issue.  See the RFC or talk to
    Andrew> Robert if you're curious about this piece of HTTP/1.1
    Andrew> esoterica.)

In a few words, 'Expect' allows the client to send its requests
(POST, PUT, whatever request that have a body) in two steps:

- the request itself,

- the body,

It's interesting in case where, for example, I want to PUT a
630MO file /dir/file, but the 'dir' does not exist. The server
can reply with an error before I even begin to send the 630MO
part, huge win. 

But in smart server case, net loss.

    Vincent