Added a client-storage check to make sure a client doesn't connect to

an out-of-date server.

src/ZEO/ClientStorage.py

@@ -1219,6 +1219,10 @@ class ClientStorage(object):
                 log2("No verification necessary (last_inval_tid up-to-date)")
                 self.finish_verification()
                 return "no verification"
+            elif ltid < last_inval_tid:
+                message = "Client has seen newer trasnactions than server!"
+                log2(message, level=logging.CRITICAL)
+                raise ClientStorageError(message)
 
             # log some hints about last transaction
             log2("last inval tid: %r %s\n"

src/ZEO/tests/zeo-fan-out.test

@@ -4,7 +4,7 @@ ZEO Fan Out
 We should be able to set up ZEO servers with ZEO clients.  Let's see
 if we can make it work.
 
-We'll use some helper functions.  The first is a helpter that starts
+We'll use some helper functions.  The first is a helper that starts
 ZEO servers for us and another one that picks ports.
 
 We'll start the first server:
@@ -13,7 +13,8 @@ We'll start the first server:
     >>> port0 = ZEO.tests.testZEO.get_port()
     >>> zconf0 = ZEO.tests.forker.ZEOConfig(('', port0))
     >>> zport0, adminaddr0, pid0, path0 = ZEO.tests.forker.start_zeo_server(
-    ...    '<filestorage 1>\n  path fs\n</filestorage>\n', zconf0, port0)
+    ...    '<filestorage 1>\n  path fs\n</filestorage>\n', zconf0,
+    ...    port0, keep=1)
 
 
 Then we''ll start 2 others that use this one:
@@ -56,13 +57,6 @@ And some databases and connections around these:
     >>> r2
     {}
 
-    >>> db2 = DB(cs2)
-    >>> tm2 = transaction.TransactionManager()
-    >>> c2 = db2.open(transaction_manager=tm2)
-    >>> r2 = c2.root()
-    >>> r2
-    {}
-
 If we update c1, we'll eventually see the change in c2:
 
     >>> import persistent.mapping