Switch back to decimal MB, to match the actual ZEO default. Change

the BuddyCacheSimulation constructor to round up the cachelimit so
that it reports the actual value used.

src/ZEO/simul.py

@@ -39,7 +39,7 @@ def usage(msg):
 
 def main():
     # Parse options
-    MB = 1024*1024
+    MB = 1000*1000
     cachelimit = 20*MB
     simclass = ZEOCacheSimulation
     try:
@@ -387,6 +387,9 @@ class Node:
 
 class BuddyCacheSimulation(LRUCacheSimulation):
 
+    def __init__(self, cachelimit):
+        LRUCacheSimulation.__init__(self, roundup(cachelimit))
+
     def restart(self):
         LRUCacheSimulation.restart(self)
         self.allocator = self.allocatorFactory(self.cachelimit)