use EscapedPath instead of Path

[wansing]

Way can't distinguish between / and %2F in a path. Thus %2F messes up the path segments.

I'd suggest to fix this by using u.EscapedPath() instead of req.URL.Path. Quoting net/url#URL:

Note that the Path field is stored in decoded form: /%47%6f%2f becomes /Go/. A consequence is that it is impossible to tell which slashes in the Path were slashes in the raw URL and which were %2f. This distinction is rarely important, but when it is, the code should use the EscapedPath method, which preserves the original encoding of Path.