py3: make sure we are doing integer division by using '//'

Differential Revision: https://phab.mercurial-scm.org/D2337

mercurial/crecord.py

@@ -1335,7 +1335,7 b' class curseschunkselector(object):'
         # temporarily disable printing to windows by printstring
         patchdisplaystring = self.printitem(item, ignorefolding,
                                             recursechildren, towin=False)
-        numlines = len(patchdisplaystring) / self.xscreensize
+        numlines = len(patchdisplaystring) // self.xscreensize
         return numlines
 
     def sigwinchhandler(self, n, frame):