Do not clear hostPid for host-networked container

pkg/kubelet/dockershim/security_context.go

@@ -167,7 +167,6 @@ func modifyHostNetworkOptionForContainer(hostNetwork bool, sandboxID string, hc
 	hc.NetworkMode = dockercontainer.NetworkMode(sandboxNSMode)
 	hc.IpcMode = dockercontainer.IpcMode(sandboxNSMode)
 	hc.UTSMode = ""
-	hc.PidMode = ""
 
 	if hostNetwork {
 		hc.UTSMode = namespaceModeHost

pkg/kubelet/dockershim/security_context_test.go

@@ -306,6 +306,7 @@ func TestModifyContainerNamespaceOptions(t *testing.T) {
 			expected: &dockercontainer.HostConfig{
 				NetworkMode: dockercontainer.NetworkMode(sandboxNSMode),
 				IpcMode:     dockercontainer.IpcMode(sandboxNSMode),
+				PidMode:     namespaceModeHost,
 			},
 		},
 	}