Fix invalid and infinite redirect for unsupported browsers

Conflicts:

	program/js/app.js

program/js/app.js

@@ -142,7 +142,7 @@ function rcube_webmail()
     this.task = this.env.task;
 
     // check browser
-    if (!bw.dom || !bw.xmlhttp_test() || (bw.mz && bw.vendver < 1.9)) {
+    if (this.env.server_error != 409 && (!bw.dom || !bw.xmlhttp_test() || (bw.mz && bw.vendver < 1.9))) {
       this.goto_url('error', '_code=0x199');
       return;
     }
@@ -6796,7 +6796,7 @@ function rcube_webmail()
         param[k] = query[k];
     }
 
-    return base + '&' + $.param(param) + querystring;
+    return base + (base.indexOf('?') > -1 ? '&' : '?') + $.param(param) + querystring;
   };
 
   this.redirect = function(url, lock)