Revision 1866899

When following an HTTP redirect, use the Location header URL exactly.

Previously we canonicalized the redirect URL, which could lead to a redirect
loop. Then Subversion would report a redirect loop as the error, potentially
hiding a more interesting error such as when the target is not in fact a
Subversion repository.

A manual test case (on a non-repository):
  before:
    $ svn ls https://archive.apache.org/dist
    Redirecting to URL 'https://archive.apache.org/dist':
    Redirecting to URL 'https://archive.apache.org/dist':
    svn: E195019: Redirect cycle detected for URL 'https://archive.apache.org/dist'

  after:
    $ svn ls https://archive.apache.org/dist
    Redirecting to URL 'https://archive.apache.org/dist/':
    svn: E170013: Unable to connect to a repository at URL 'https://archive.apache.org/dist/'
    svn: E175003: The server at 'https://archive.apache.org/dist/' does not support the HTTP/DAV protocol

* subversion/libsvn_ra_serf/options.c
  (svn_ra_serf__exchange_capabilities): Don't canonicalize the redirect URL.

* subversion/libsvn_ra_serf/util.c
  (response_get_location): Don't canonicalize the redirect URL.