put the development server backend and override cookie stuff into a different files

devicedetect-dev.vcl

+#
+# devicedetect-dev.vcl
+#
+# Enable test URLs and cookie overrides
+
+backend devicetest { 
+    .host = "127.0.0.1";
+    .port = "8000";
+}
+
+sub vcl_recv {
+    if (req.url ~ "^/set_devicetype/") { error 701 regsub(req.url, "^/set_devicetype/", ""); }
+    if (req.url ~ "^/devicetest") { set backend = devicetest; }
+}
+
+sub vcl_error { 
+    if (obj.status == 701 ) {
+        # obj.response == mobile-generic
+        set obj.http.Set-Cookie = "X-UA-device=" + obj.response;
+        set obj.http.Content-Type = "text/plain; charset=utf-8";
+        synthetic {" 200 OK, Cookie set "};
+	return(deliver)
+    }
+}
+"""