https: Quote path in URL before passing it to curl

https: Quote path in URL before passing it to curl

Curl requires URLs to be urlencoded. We are however giving it
undecoded URLs. This causes it go completely nuts if there is
a space in the URI, producing requests like:

    GET /a file HTTP/1.1

which the servers then interpret as a GET request for "/a" with
HTTP version "file" or some other non-sense.

This works around the issue by encoding the path component of
the URL. I'm not sure if we should encode other parts of the URL
as well, this one seems to do the trick for the actual issue at
hand.

A more correct fix is to avoid the dequoting and (re-)quoting
of URLs when a redirect occurs / a new request is sent. That's
been on the radar for probably a year or two now, but nobody
bothered implementing that yet.

LP: #1651923
(cherry picked from commit 994515e689dcc5f963f5fed58284831750a5da03)