Create packages client/internal/ retry and lhttp.

client/cmd/isolate/common.go

Index: client/cmd/isolate/common.go
diff --git a/client/cmd/isolate/common.go b/client/cmd/isolate/common.go
index 2a72623238ffdb1e72fc589fe7b8a36e8e5a6057..6dd4a4d085013bb9d3be128522be056130f0cd3f 100644
--- a/client/cmd/isolate/common.go
+++ b/client/cmd/isolate/common.go
@@ -13,6 +13,7 @@ import (
 	"os"
 
 	"github.com/luci/luci-go/client/internal/common"
+	"github.com/luci/luci-go/client/internal/lhttp"
 	"github.com/luci/luci-go/client/internal/tracer"
 	"github.com/luci/luci-go/client/isolate"
 	"github.com/maruel/subcommands"
@@ -81,7 +82,7 @@ func (c *commonServerFlags) Parse() error {
 	if c.serverURL == "" {
 		return errors.New("-isolate-server must be specified")
 	}
-	if s, err := common.URLToHTTPS(c.serverURL); err != nil {
+	if s, err := lhttp.URLToHTTPS(c.serverURL); err != nil {
 		return err
 	} else {
 		c.serverURL = s