log: do not redefine cachefunc in walkchangerevs

The same variable is defined a few blocks earlier. The first phases in
walkchangerevs should in fact fill that cache, and allow faster lookups
in the last phase. Redefining and overriding this cached function, (knowing
that it will be called with the same arguments) defeats the caching purpose.

mercurial/cmdutil.py

@@ -1182,7 +1182,6 b' def walkchangerevs(repo, match, opts, pr'
                 return rev in wanted
 
         for i, window in increasing_windows(0, len(revs)):
-            change = util.cachefunc(repo.changectx)
             nrevs = [rev for rev in revs[i:i + window] if want(rev)]
             for rev in sorted(nrevs):
                 fns = fncache.get(rev)