Update cmux to 0.1.4

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>

vendor.conf

@@ -107,7 +107,7 @@ github.com/matttproud/golang_protobuf_extensions fc2b8d3a73c4867e51861bbdd5ae3c1
 github.com/beorn7/perks 3ac7bf7a47d159a033b107610db8a1b6575507a4
 github.com/containerd/cgroups 7a5fdd8330119dc70d850260db8f3594d89d6943
 github.com/go-zoo/bone 031b4005dfe248ccba241a0c9de0f9e112fd6b7c
-github.com/soheilhy/cmux v0.1.3
+github.com/soheilhy/cmux v0.1.4
 github.com/hashicorp/go-multierror 83588e72410abfbe4df460eeb6f30841ae47d4c4
 github.com/hashicorp/errwrap 7554cd9344cec97297fa6649b055a8c98c2a1e55
 github.com/pquerna/ffjson d49c2bc1aa135aad0c6f4fc2056623ec78f5d5ac

vendor/github.com/soheilhy/cmux/cmux.go

@@ -116,8 +116,9 @@ type cMux struct {
 func matchersToMatchWriters(matchers []Matcher) []MatchWriter {
 	mws := make([]MatchWriter, 0, len(matchers))
 	for _, m := range matchers {
+		cm := m
 		mws = append(mws, func(w io.Writer, r io.Reader) bool {
-			return m(r)
+			return cm(r)
 		})
 	}
 	return mws

vendor/github.com/soheilhy/cmux/matchers.go

@@ -240,6 +240,11 @@ func matchHTTP2Field(w io.Writer, r io.Reader, name string, matches func(string)
 
 		switch f := f.(type) {
 		case *http2.SettingsFrame:
+			// Sender acknoweldged the SETTINGS frame. No need to write
+			// SETTINGS again.
+			if f.IsAck() {
+				break
+			}
 			if err := framer.WriteSettings(); err != nil {
 				return false
 			}