revset: maintain ordering when subtracting from a baseset (issue4289)

mercurial/revset.py

@@ -2243,11 +2243,7 b' class baseset(list):'
         """Returns a new object with the substraction of the two collections.
 
         This is part of the mandatory API for smartset."""
-        if isinstance(other, baseset):
-            s = other.set()
-        else:
-            s = set(other)
-        return baseset(self.set() - s)
+        return self.filter(lambda x: x not in other)
 
     def __and__(self, other):
         """Returns a new object with the intersection of the two collections.

tests/test-revset.t

@@ -1008,6 +1008,11 b' issue2549 - correct optimizations'
   $ log 'min(1 or 2) and not 1'
   $ log 'last(1 or 2, 1) and not 2'
 
+issue4289 - ordering of built-ins
+  $ hg log -M -q -r 3:2
+  3:8528aa5637f2
+  2:5ed5505e9f1c
+
 test revsets started with 40-chars hash (issue3669)
 
   $ ISSUE3669_TIP=`hg tip --template '{node}'`