merge branch 'pr-1867'

Revert "libcontainer/rootfs_linux: minor cleanup"

LGTMs: @hqhq @cyphar
Closes #1867

libcontainer/rootfs_linux.go

@@ -46,6 +46,7 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {
 		return newSystemErrorWithCause(err, "preparing rootfs")
 	}
 
+	setupDev := needsSetupDev(config)
 	for _, m := range config.Mounts {
 		for _, precmd := range m.PremountCmds {
 			if err := mountCmd(precmd); err != nil {
@@ -64,8 +65,6 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {
 		}
 	}
 
-	setupDev := needsSetupDev(config)
-
 	if setupDev {
 		if err := createDevices(config); err != nil {
 			return newSystemErrorWithCause(err, "creating device nodes")