[MERGE][ping] Better connection sharing for pycurl

[Vincent Ladeuil]

>>>>> "vila" == Vincent Ladeuil <v.ladeuil at alplog.fr> writes:

<snip/>

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

    vila> - the request itself,

    vila> - the body,

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

    vila> But in smart server case, net loss.

I failed to mention that not all servers support the Expect
header, in which case pycurl send the body after a predefined
timeout.

I think we should support that as we support the range
capabilities, i.e. detect the server capability and act
accordingly.

Small priority, but that may help a lot in DAV.

      Vincent