Clean path in serverMux should apply to raw path

[gopherbot]

by hongruiqi:

What steps will reproduce the problem?
http.Handle("/test///a", Handler)
And visit http://localhost/test/%2f/a

What is the expected output?
Handler should be called.

What do you see instead?
The browser is redirected to /test/a, and a 404 error

Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
linux

Which version are you using?  (run 'go version')
go version devel +0d9fd828f099 Wed Jan 30 17:26:22 2013 +1100 linux/amd64.

Please provide any additional information below.

if p := cleanPath(path); p != path {
    _, pattern = mux.handler(r.Host, p)
    return RedirectHandler(p, StatusMovedPermanently), pattern
}

If path is a raw path before unescape，/test/%2f/a can be handled correctly without
redirect. mux.match can use r.URL.Path as before.

[rsc]

Comment 1:

The HTTP server has no way to distinguish /test/%2f/a from /test///a. There is a pending
issue to document this property in net/url better. I am marking this issue a duplicate
of that one.

Status changed to Duplicate.

Merged into issue #3659.