Error given multiple times on specific website

[pmeenan]

Try turning on the "preserve user agent string" field in the advanced settings. Looks like the security for that site may be turned up pretty tight and it is probably blocking access based of the PTST/ string that gets added to the UA string (or it could be blocking access from the IP addresses).

Not a bug with WPT itself, the site is actively blocking access which is what 403's usually are.