GET /x/net
code == 200
body contains <meta name="go-import" content="golang.org/x/net git https://go.googlesource.com/net">
body contains http-equiv="refresh" content="0; url=https://pkg.go.dev/golang.org/x/net">

GET /x/net/suffix
code == 200
body contains <meta name="go-import" content="golang.org/x/net git https://go.googlesource.com/net">
body contains http-equiv="refresh" content="0; url=https://pkg.go.dev/golang.org/x/net/suffix">

GET /x/pkgsite
code == 200
body contains <meta name="go-import" content="golang.org/x/pkgsite git https://go.googlesource.com/pkgsite">
body contains <a href="https://pkg.go.dev/golang.org/x/pkgsite">Redirecting to documentation...</a>
body contains http-equiv="refresh" content="0; url=https://pkg.go.dev/golang.org/x/pkgsite">

GET /x/notexist
code == 404

GET /x/
code == 307
header location == https://pkg.go.dev/search?q=golang.org/x

GET /x/In%20Valid,X
code == 404