This might be a non bug. Certain proxies add domains (including new TLDs) for "internal" URLs, so the location bar shouldn't be interfering. Since the proxy is returning an error page with content (and possibly with the wrong error code), Firefox can't simply hide the error page and move on to search.
This might be a non bug. Certain proxies add domains (including new TLDs) for "internal" URLs, so the location bar shouldn't be interfering. Since the proxy is returning an error page with content (and possibly with the wrong error code), Firefox can't simply hide the error page and move on to search.