Bug Fixed

 Updating blobs in save points could cause spurious "invalidations
 out of order" errors.  https://bugs.launchpad.net/zodb/+bug/509801

(Thanks to Christian Zagrodnick for chasing this down.)

NEWS.txt

@@ -4,6 +4,11 @@ Whats new in ZODB 3.8.6 (2010-??-??)
 
 Bugs Fixed:
 
+- Updating blobs in save points could cause spurious "invalidations
+  out of order" errors.  https://bugs.launchpad.net/zodb/+bug/509801
+
+  (Thanks to Christian Zagrodnick for chasing this down.)
+
 - BTree sets and tree sets didn't correctly check values passed to
   update or to constructors, causing Python to exit under certain
   circumstances.

src/ZODB/Connection.py

@@ -332,7 +332,7 @@ class Connection(ExportImport, object):
         try:
             if self._txn_time is None:
                 self._txn_time = tid
-            elif tid < self._txn_time:
+            elif (tid < self._txn_time) and (tid is not None):
                 raise AssertionError("invalidations out of order, %r < %r"
                                      % (tid, self._txn_time))
 
@@ -346,7 +346,7 @@ class Connection(ExportImport, object):
             self._invalidatedCache = True
         finally:
             self._inv_lock.release()
-        
+
 
     def root(self):
         """Return the database root object."""
@@ -1137,7 +1137,7 @@ class Connection(ExportImport, object):
                 # that that the next attribute access of its name
                 # unghostify it, which will cause its blob data
                 # to be reattached "cleanly"
-                self.invalidate(s, {oid:True})
+                self.invalidate(None, (oid, ))
             else:
                 s = self._storage.store(oid, serial, data,
                                         self._version, transaction)

src/ZODB/tests/testblob.py

@@ -539,6 +539,44 @@ def loadblob_tmpstore():
     >>> os.unlink(storagefile+".tmp")
 """
 
+def savepoint_commits_without_invalidations_out_of_order():
+    """Make sure transactions with blobs can be commited without the
+    invalidations out of order error (LP #509801)
+
+    >>> from ZODB.MappingStorage import MappingStorage
+    >>> from ZODB.blob import BlobStorage
+    >>> from ZODB.DB import DB
+    >>> from ZODB.serialize import referencesf
+    >>> from tempfile import mkdtemp
+
+    >>> base_storage = MappingStorage("test")
+    >>> blob_dir = mkdtemp()
+    >>> blob_storage = BlobStorage(blob_dir, base_storage)
+    >>> db = DB(blob_storage)
+    >>> tm1 = transaction.TransactionManager()
+    >>> conn1 = db.open(transaction_manager=tm1)
+    >>> conn1.root()['b'] = ZODB.blob.Blob()
+    >>> conn1.root()['b'].open('w').write('initial')
+    >>> tm1.commit()
+    >>> conn1.root()['b'].open('w').write('1')
+    >>> _ = tm1.savepoint()
+
+    >>> tm2 = transaction.TransactionManager()
+    >>> conn2 = db.open(transaction_manager=tm2)
+    >>> conn2.root()['b'].open('w').write('2')
+    >>> _ = tm1.savepoint()
+    >>> conn1.root()['b'].open().read()
+    '1'
+    >>> conn2.root()['b'].open().read()
+    '2'
+    >>> tm2.commit()
+    >>> tm1.commit()  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+        ...
+    ConflictError: database conflict error...
+    >>> db.close()
+    """
+
 def setUp(test):
     ZODB.tests.util.setUp(test)
     def rmtree(path):