Only insert in lists instead of replacing

percy/render/recipe.py

@@ -774,14 +774,17 @@ def _patch(self, operation):
                     match_lines[i] = m
         match_lines = dict(sorted(match_lines.items(), reverse=True))
 
-        # remove elements and find insert position
         new_range = deepcopy(range)
         insert_index = 0
         index_set = False
-        for i, m in match_lines.items():
-            new_range.pop(i)
-            insert_index = i
-            index_set = True
+        # remove elements
+        if op == "remove":
+            for i, m in match_lines.items():
+                new_range.pop(i)
+                insert_index = i
+                index_set = True
+
+        # Find insert position
         range = new_range
         if not index_set:
             for i, e in reversed(list(enumerate(range))):