fix stringstack & MoveStage error

common/stringstack/stringstack.go

@@ -6,8 +6,7 @@ import (
 
 // StringStack is a basic LIFO "stack" for storing strings.
 type StringStack struct {
-	Locked bool
-	stack  []string
+	stack []string
 }
 
 // New creates a new instance of StringStack
@@ -20,20 +19,6 @@ func (s *StringStack) Set(v string) {
 	s.stack = []string{v}
 }
 
-// Lock freezes the StringStack
-func (s *StringStack) Lock() {
-	if !s.Locked {
-		s.Locked = true
-	}
-}
-
-// Unlock unfreezes the StringStack
-func (s *StringStack) Unlock() {
-	if s.Locked {
-		s.Locked = false
-	}
-}
-
 // Push pushes a string onto the stack.
 func (s *StringStack) Push(v string) {
 	s.stack = append(s.stack, v)