no proxy url if pointing to self

[stevenvachon]

process.env.HTTP_PROXY = "http://proxy/";
getProxyFromUrl("http://proxy/");
//-> http://proxy/

I think that it should return undefined, since a proxy to the same proxy is redundant.

[Rob--W]

I agree that proxying an already-proxied URL is somewhat redundant, but I'm not going to add a special case for the situation because the requests are similar but not strictly equivalent. For example, the proxy might have a different DNS record for the referenced host name (compared to the resolved host name as seen by the client).