command/format: take noop changes from lcs

When rendering the diff, the NoOp changes should come from the LCS
sequence, rather than the new sequence. The two indexes will not align
in many cases, adding the wrong new object or indexing out of bounds.

command/format/diff.go

@@ -1101,8 +1101,8 @@ func ctySequenceDiff(old, new []cty.Value) []*plans.Change {
 		if lcsI < len(lcs) {
 			ret = append(ret, &plans.Change{
 				Action: plans.NoOp,
-				Before: new[newI],
-				After:  new[newI],
+				Before: lcs[lcsI],
+				After:  lcs[lcsI],
 			})
 
 			// All of our indexes advance together now, since the line

command/format/diff_test.go

@@ -3006,6 +3006,49 @@ func TestResourceChange_nestedMap(t *testing.T) {
           - volume_type = "gp2" -> null
         }
     }
+`,
+		},
+		"in-place sequence update - deletion": {
+			Action: plans.Update,
+			Mode:   addrs.ManagedResourceMode,
+			Before: cty.ObjectVal(map[string]cty.Value{
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{"attr": cty.StringVal("x")}),
+					cty.ObjectVal(map[string]cty.Value{"attr": cty.StringVal("y")}),
+				}),
+			}),
+			After: cty.ObjectVal(map[string]cty.Value{
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{"attr": cty.StringVal("y")}),
+					cty.ObjectVal(map[string]cty.Value{"attr": cty.StringVal("z")}),
+				}),
+			}),
+			RequiredReplace: cty.NewPathSet(),
+			Tainted:         false,
+			Schema: &configschema.Block{
+				BlockTypes: map[string]*configschema.NestedBlock{
+					"list": {
+						Block: configschema.Block{
+							Attributes: map[string]*configschema.Attribute{
+								"attr": {
+									Type:     cty.String,
+									Required: true,
+								},
+							},
+						},
+						Nesting: configschema.NestingList,
+					},
+				},
+			},
+			ExpectedOutput: `  # test_instance.example will be updated in-place
+  ~ resource "test_instance" "example" {
+      ~ list {
+          ~ attr = "x" -> "y"
+        }
+      ~ list {
+          ~ attr = "y" -> "z"
+        }
+    }
 `,
 		},
 	}