Support websites redirecting to the same page when AllowURLRevisit is disabled

[WGH-]

Some websites set a session cookie, and return a redirect to the same page instead of returning a response.

To illustrate this problem, this is how HTTP session might look like:

GET / HTTP/1.1
Host: 127.0.0.1:34931
User-Agent: colly - https://github.com/gocolly/colly/v2
Accept: */*
Accept-Encoding: gzip

HTTP/1.1 302 Found
Content-Type: text/html; charset=utf-8
Location: /
Set-Cookie: session_id=1
Date: Mon, 10 Apr 2023 23:29:29 GMT
Content-Length: 24

<a href="/">Found</a>.

GET / HTTP/1.1
Host: 127.0.0.1:34931
User-Agent: colly - https://github.com/gocolly/colly/v2
Accept: */*
Cookie: session_id=1
Referer: http://127.0.0.1:34931/
Accept-Encoding: gzip

HTTP/1.1 200 OK
Date: Mon, 10 Apr 2023 23:29:29 GMT
Content-Length: 12
Content-Type: text/plain; charset=utf-8

hello world

This fixes regression introduced in 0be3b71 by specifically bypassing revisit check if current redirect destination equals to the original one.

[asciimoo]

LGTM, thanks <3