Merge pull request #76 from calavera/fix_canceler_14_conversion

Fix implicit conversion of transport sender in canceler_14.

client/transport/cancellable/canceler_go14.go

@@ -16,7 +16,7 @@ type requestCanceler interface {
 	CancelRequest(*http.Request)
 }
 
-func canceler(client transport.Client, req *http.Request) func() {
+func canceler(client transport.Sender, req *http.Request) func() {
 	rc, ok := client.(requestCanceler)
 	if !ok {
 		return func() {}

client/transport/cancellable/cancellable.go

@@ -36,7 +36,7 @@ func Do(ctx context.Context, client transport.Sender, req *http.Request) (*http.
 		client = http.DefaultClient
 	}
 
-	// Request cancelation changed in Go 1.5, see cancelreq.go and cancelreq_go14.go.
+	// Request cancelation changed in Go 1.5, see canceler.go and canceler_go14.go.
 	cancel := canceler(client, req)
 
 	type responseAndError struct {