Drop backward compatibility with older ZODB.

Update README to set minimum ZODB version instead of minimum Zope version.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2507 71dcc9de-d417-0410-9af5-da40c76e7ee4

README

@@ -11,7 +11,7 @@ Requirements
 
     - MySQLdb http://sourceforge.net/projects/mysql-python
 
-    - Zope 2.8 or later
+    - ZODB 3.10 or later (required python 2.5 or later, only for client nodes)
 
 Overview
 

neo/client/app.py

@@ -64,13 +64,6 @@ else:
     compress = real_compress
     makeChecksum = real_makeChecksum
 
-# Set environment variable to non-empty value to ignore:
-# - multiple calls to tpc_begin for same transaction
-# - tpc_finish called for different transaction
-# This is needed to conform to the "old" ZODB API (ex: 3.4).
-RELAX_TRANSACTION_CHECKS = bool(os.getenv('NEO_RELAX_TRANSACTION_CHECKS',
-    False))
-
 class ThreadContext(object):
 
     def __init__(self):
@@ -606,8 +599,6 @@ class Application(object):
         # First get a transaction, only one is allowed at a time
         if self.local_var.txn is transaction:
             # We already begin the same transaction
-            if RELAX_TRANSACTION_CHECKS:
-                return
             raise StorageTransactionError('Duplicate tpc_begin calls')
         if self.local_var.txn is not None:
             raise NeoException, 'local_var is not clean in tpc_begin'
@@ -865,8 +856,6 @@ class Application(object):
         """Finish current transaction."""
         local_var = self.local_var
         if local_var.txn is not transaction:
-            if RELAX_TRANSACTION_CHECKS:
-                return
             raise StorageTransactionError('tpc_finish called for wrong '
                 'transaction')
         if not local_var.txn_voted: