tuning: always update MAC in CNI result

Since the CNI Spec bump to v1.0 the tuning plugin no longer updates the
mac address in the cni result for 0.4.0 or below configs. I don't think
this ever worked when the cni result was converted to a different version.

A test has been added to ensure it is working for all spec versions.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

plugins/meta/tuning/tuning_test.go

@@ -465,11 +465,12 @@ var _ = Describe("tuning plugin", func() {
 		})
 
 		It(fmt.Sprintf("[%s] configures and deconfigures mac address (from conf file) with ADD/DEL", ver), func() {
+			mac := "c2:11:22:33:44:55"
 			conf := []byte(fmt.Sprintf(`{
 				"name": "test",
 				"type": "iplink",
 				"cniVersion": "%s",
-				"mac": "c2:11:22:33:44:55",
+				"mac": "%s",
 				"prevResult": {
 					"interfaces": [
 						{"name": "dummy0", "sandbox":"netns"}
@@ -483,7 +484,7 @@ var _ = Describe("tuning plugin", func() {
 						}
 					]
 				}
-			}`, ver))
+			}`, ver, mac))
 
 			args := &skel.CmdArgs{
 				ContainerID: "dummy",
@@ -508,9 +509,10 @@ var _ = Describe("tuning plugin", func() {
 				Expect(len(result.IPs)).To(Equal(1))
 				Expect(result.IPs[0].Address.String()).To(Equal("10.0.0.2/24"))
 
+				Expect(result.Interfaces[0].Mac).To(Equal(mac))
 				link, err := netlink.LinkByName(IFNAME)
 				Expect(err).NotTo(HaveOccurred())
-				hw, err := net.ParseMAC("c2:11:22:33:44:55")
+				hw, err := net.ParseMAC(mac)
 				Expect(err).NotTo(HaveOccurred())
 				Expect(link.Attrs().HardwareAddr).To(Equal(hw))