stop infinite loop in opening authenticated url.  (ctl.redirectlimit makes
it appear that we're not looping because clientbody open tries to
return an incomplete result if possible.)

Reference: /n/sources/patch/applied/webfsauthloop
Date: Mon Apr 14 06:06:21 CES 2008
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/webfs/http.c	Mon Apr 14 06:05:05 2008
+++ /sys/src/cmd/webfs/http.c	Mon Apr 14 06:05:04 2008
@@ -483,7 +483,8 @@
 		}
 		c->authenticate = hs->credentials;
 		hs->credentials = nil;
-	}
+	}else if(c->authenticate)
+		c->authenticate = 0;
 	if(redirect){
 		if(!hs->location){
 			werrstr("redirection without Location: header");