Fix issue with looping in list merging

The last_dest_idx variable should always have been
tracking the last index in the source list. The
original intention, implemented incorrectly, was
to just append any items which source has no item
at that index.

app/utils.py

@@ -651,9 +651,9 @@ def merge_jsonlike(source, destination):
         return True
 
     def merge_lists(source, destination):
-        last_dest_idx = len(destination) - 1
+        last_src_idx = len(source) - 1
         for idx, item in enumerate(destination):
-            if idx <= last_dest_idx:
+            if idx <= last_src_idx:
                 # assign destination value if can't be merged into source
                 if merge_items(source[idx], destination[idx]) is False:
                     source[idx] = destination[idx]