Merge branch 'jk/http-walker-limit-redirect-2.9'

Transport with dumb http can be fooled into following foreign URLs
that the end user does not intend to, especially with the server
side redirects and http-alternates mechanism, which can lead to
security issues.  Tighten the redirection and make it more obvious
to the end user when it happens.

* jk/http-walker-limit-redirect-2.9:
  http: treat http-alternates like redirects
  http: make redirects more obvious
  remote-curl: rename shadowed options variable
  http: always update the base URL for redirects
  http: simplify update_url_from_redirect

t/t5551-http-fetch-smart.sh

@@ -119,6 +119,10 @@ test_expect_success 'redirects re-root further requests' '
 	git clone $HTTPD_URL/smart-redir-limited/repo.git repo-redir-limited
 '
 
+test_expect_success 're-rooting dies on insane schemes' '
+	test_must_fail git clone $HTTPD_URL/insane-redir/repo.git insane
+'
+
 test_expect_success 'clone from password-protected repository' '
 	echo two >expect &&
 	set_askpass user@host pass@host &&