revset: extend sorting tests

tests/test-revset.t

@@ -483,7 +483,6 b' test when sorting a reversed collection '
   1
   0
 
-
 test when sorting a reversed collection
 
   $ log 'sort(reverse(all()), rev)'
@@ -515,6 +514,20 b' test sorting two sorted collections in d'
   6
   2
 
+test substracting something from an addset
+
+  $ log '(outgoing() or removes(a)) - removes(a)'
+  8
+  9
+
+test intersecting something with an addset
+
+  $ log 'parents(outgoing() or removes(a))'
+  1
+  4
+  5
+  8
+
 check that conversion to _missingancestors works
   $ try --optimize '::3 - ::1'
   (minus