panic: net/http: CloseNotify called after ServeHTTP finished

    goroutine 180 [running]:
    net/http.(*response).CloseNotify(0xc8220684e0, 0x0)
        /home/r/go/src/net/http/server.go:1535 +0x9d
    github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/prometheus/client_golang/
        /home/r/src/github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/prome
    github.com/ipfs/go-ipfs/core/corehttp.(*gatewayHandler).getOrHeadHandler.func1(0x7
        /home/r/src/github.com/ipfs/go-ipfs/core/corehttp/gateway_handler.go:119 +
    created by github.com/ipfs/go-ipfs/core/corehttp.(*gatewayHandler).getOrHeadHandle
        /home/r/src/github.com/ipfs/go-ipfs/core/corehttp/gateway_handler.go:123 +

License: MIT
Signed-off-by: Robert Carlsen <rwcarlsen@gmail.com>