revset: make balanced addsets by orset() without using _combinesets()

As scmutil.revrange() was rewritten to not use _combinesets(), we no longer
need _combinesets().

mercurial/revset.py

@@ -406,8 +406,13 b' def andset(repo, subset, x, y):'
     return getset(repo, getset(repo, subset, x), y)
 
 def orset(repo, subset, *xs):
-    rs = [getset(repo, subset, x) for x in xs]
-    return _combinesets(rs)
+    assert xs
+    if len(xs) == 1:
+        return getset(repo, subset, xs[0])
+    p = len(xs) // 2
+    a = orset(repo, subset, *xs[:p])
+    b = orset(repo, subset, *xs[p:])
+    return a + b
 
 def notset(repo, subset, x):
     return subset - getset(repo, subset, x)
@@ -3107,20 +3112,6 b' class filteredset(abstractsmartset):'
     def __repr__(self):
         return '<%s %r>' % (type(self).__name__, self._subset)
 
-# this function will be removed, or merged to addset or orset, when
-# - scmutil.revrange() can be rewritten to not combine calculated smartsets
-# - or addset can handle more than two sets without balanced tree
-def _combinesets(subsets):
-    """Create balanced tree of addsets representing union of given sets"""
-    if not subsets:
-        return baseset()
-    if len(subsets) == 1:
-        return subsets[0]
-    p = len(subsets) // 2
-    xs = _combinesets(subsets[:p])
-    ys = _combinesets(subsets[p:])
-    return addset(xs, ys)
-
 def _iterordered(ascending, iter1, iter2):
     """produce an ordered iteration from two iterators with the same order