Merge rev 27557 from 3.3 branch.

New test checkReadConflictErrorClearedDuringAbort().

This confirms that 3.3 didn't have the 3.2.4c1 bug wherein
an explict transaction abort() failed to clear Connections'
memory of ReadConflictErrors.

NEWS.txt

+What's new in ZODB3 3.3?
+========================
+Release date: DD-Sep-2004
+
+
 What's new in ZODB3 3.3 release candidate 1?
 ============================================
 Release date: 14-Sep-2004

src/ZODB/tests/testZODB.py

@@ -359,6 +359,49 @@ class ZODBTests(unittest.TestCase):
         self.obj = DecoyIndependent()
         self.readConflict()
 
+    def checkReadConflictErrorClearedDuringAbort(self):
+        # When a transaction is aborted, the "memory" of which
+        # objects were the cause of a ReadConflictError during
+        # that transaction should be cleared.
+        root = self._db.open(mvcc=False).root()
+        data = PersistentMapping({'d': 1})
+        root["data"] = data
+        transaction.commit()
+
+        # Provoke a ReadConflictError.
+        tm2 = transaction.TransactionManager()
+        cn2 = self._db.open(mvcc=False, txn_mgr=tm2)
+        r2 = cn2.root()
+        data2 = r2["data"]
+
+        data['d'] = 2
+        transaction.commit()
+
+        try:
+            data2['d'] = 3
+        except ReadConflictError:
+            pass
+        else:
+            self.fail("No conflict occurred")
+
+        # Explicitly abort cn2's transaction.
+        tm2.get().abort()
+
+        # cn2 should retain no memory of the read conflict after an abort(),
+        # but 3.2.3 had a bug wherein it did.
+        data_conflicts = data._p_jar._conflicts
+        data2_conflicts = data2._p_jar._conflicts
+        self.failIf(data_conflicts)
+        self.failIf(data2_conflicts)  # this used to fail
+
+        # And because of that, we still couldn't commit a change to data2['d']
+        # in the new transaction.
+        cn2.sync()  # process the invalidation for data2['d']
+        data2['d'] = 3
+        tm2.get().commit()  # 3.2.3 used to raise ReadConflictError
+
+        cn2.close()
+
     def checkTxnBeginImpliesAbort(self):
         # begin() should do an abort() first, if needed.
         cn = self._db.open()