tests: add test to make sure subtree is being modified properly in +del-span

pkg/arvo/sys/zuse.hoon

@@ -5413,7 +5413,7 @@
       ?:  ?&(?=(~ b) =(c 0))
         [0 ~]
       =|  f=[d=@ e=(list item)]
-      |-  ^-  [d=@ e=(list item)]
+      |-  ^+  f
       ?:  ?|(?=(~ a) =(d.f c))  f
       =.  f  $(a l.a)
       ?:  =(d.f c)  f

pkg/arvo/tests/sys/zuse/ordered-map.hoon

@@ -84,6 +84,14 @@
     !>  small-test-items
     !>  (tab:atom-map a ~ 3)
 ::
+++  test-ordered-map-tab-more-than-exist  ^-  tang
+  ::
+  =/  a=(tree [@ud @tas])  (gas:atom-map ~ test-items)
+  ::
+  %+  expect-eq
+    !>  test-items
+    !>  (tab:atom-map a [~ 0] 8)
+::
 ++  test-ordered-map-pop  ^-  tang
   ::
   =/  a=(tree [@ud @tas])  (gas:atom-map ~ test-items)