Hello,

url-retrieve-synchronously fails to obey redirect responses if the
returned "Location" header contains spaces: it redirects to the URL
truncated to the first space. It seems that spaces in the Location
header value are allowed (at least ngnix produces headers like that).

If I understand the code correctly, the redirect response in interpreted
in url-http-parse-headers where the header is explicitly truncated:

	 (when redirect-uri
	   ;; Clean off any whitespace and/or <...> cruft.
	   (if (string-match "\\([^ \t]+\\)[ \t]" redirect-uri)
	       (setq redirect-uri (match-string 1 redirect-uri)))
	   (if (string-match "^<\\(.*\\)>$" redirect-uri)
	       (setq redirect-uri (match-string 1 redirect-uri)))

I think the first regular expression is wrong. I believe that its intent
is to remove leading and trailing white space, but it actually truncates
the value to the first white space character. Also, redirect-uri is
obtained with

       (let ((redirect-uri (or (mail-fetch-field "Location")
			       (mail-fetch-field "URI"))))

and mail-fetch-field already removes leading and trailing whitespace.

I think the attached patch should fix the problem.

Finally, the removal of the < > delimiters seems unnecessary too as they
are not allowed delimiters in HTTP headers (in my reading of
https://tools.ietf.org/html/rfc7230) however there are no adverse
consequences in leaving it there.

Cheers,
Dan