Filter nil Deposed values during State init

The Deposed slice wasn't being normalized and nil values could be read
in from a state file. Filter out the nils during init. There is
still a bug in copystructure, but that will be addressed separately.

terraform/state.go

@@ -1403,9 +1403,18 @@ func (s *ResourceState) init() {
 		s.Deposed = make([]*InstanceState, 0)
 	}
 
-	for _, dep := range s.Deposed {
-		dep.init()
+	// clean out any possible nil values read in from the state file
+	end := len(s.Deposed) - 1
+	for i := 0; i <= end; i++ {
+		if s.Deposed[i] == nil {
+			s.Deposed[i], s.Deposed[end] = s.Deposed[end], s.Deposed[i]
+			end--
+			i--
+		} else {
+			s.Deposed[i].init()
+		}
 	}
+	s.Deposed = s.Deposed[:end+1]
 }
 
 func (s *ResourceState) deepcopy() *ResourceState {

terraform/state_test.go

@@ -283,6 +283,8 @@ func TestStateDeepCopy(t *testing.T) {
 			},
 		},
 		// Deposed
+		// The nil values shouldn't be there if the State was properly init'ed,
+		// but the Copy should still work anyway.
 		{
 			&State{
 				Version: 6,