diff -r c10c87c8fe79 -r 508dfd1c18df mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Wed Sep 09 17:04:44 2020 +0900
+++ b/mercurial/cmdutil.py	Sun Oct 04 13:17:57 2020 +0900
@@ -2240,55 +2240,6 @@
     return b'%d' % rev
 
 
-def increasingwindows(windowsize=8, sizelimit=512):
-    while True:
-        yield windowsize
-        if windowsize < sizelimit:
-            windowsize *= 2
-
-
-def walkchangerevs(repo, revs, makefilematcher, prepare):
-    '''Iterate over files and the revs in a "windowed" way.
-
-    Callers most commonly need to iterate backwards over the history
-    in which they are interested. Doing so has awful (quadratic-looking)
-    performance, so we use iterators in a "windowed" way.
-
-    We walk a window of revisions in the desired order.  Within the
-    window, we first walk forwards to gather data, then in the desired
-    order (usually backwards) to display it.
-
-    This function returns an iterator yielding contexts. Before
-    yielding each context, the iterator will first call the prepare
-    function on each context in the window in forward order.'''
-
-    if not revs:
-        return []
-    change = repo.__getitem__
-
-    def iterate():
-        it = iter(revs)
-        stopiteration = False
-        for windowsize in increasingwindows():
-            nrevs = []
-            for i in pycompat.xrange(windowsize):
-                rev = next(it, None)
-                if rev is None:
-                    stopiteration = True
-                    break
-                nrevs.append(rev)
-            for rev in sorted(nrevs):
-                ctx = change(rev)
-                prepare(ctx, makefilematcher(ctx))
-            for rev in nrevs:
-                yield change(rev)
-
-            if stopiteration:
-                break
-
-    return iterate()
-
-
 def add(ui, repo, match, prefix, uipathfn, explicitonly, **opts):
     bad = []