revset: cosmetic changes in spanset range comparison

We use the python syntax for range comparison: `a < x < c`. This is shorter,
more readable and less error prone. This comparison escaped the cleanup make in
e2031c8ca4f8

mercurial/revset.py

@@ -2821,7 +2821,7 class spanset(_orderedsetmixin):
             start = self._start
             end = self._end
             for rev in self._hiddenrevs:
-                if (end < rev <= start) or (start <= rev and rev < end):
+                if (end < rev <= start) or (start <= rev < end):
                     count += 1
             return abs(self._end - self._start) - count