Run (make vendor)

Temporarily vendor opencontainers/image-spec from a fork
to fix "id" value duplication, which is detected and
refused by gojsonschema now
( https://github.com/opencontainers/image-spec/pull/750 ).

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/golang.org/x/net/internal/socks/socks.go

@@ -224,6 +224,7 @@ func (d *Dialer) Dial(network, address string) (net.Conn, error) {
 		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
 	}
 	if _, err := d.DialWithConn(context.Background(), c, network, address); err != nil {
+		c.Close()
 		return nil, err
 	}
 	return c, nil