- fixed an attribute history bug whereby assigning a new collection

to a collection-based attribute which already had pending changes
would generate incorrect history [ticket:922]

- fixed delete-orphan cascade bug whereby setting the same
object twice to a scalar attribute could log it as an orphan
[ticket:925]
- generative select.order_by(None) / group_by(None) was not managing to
reset order by/group by criterion, fixed [ticket:924]

2 files changed, 6 insertions, 6 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index a95ae0500..84c9dfbb6 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -251,8 +251,7 @@ class AttributeImpl(object):
     def set_committed_value(self, state, value):
         """set an attribute value on the given instance and 'commit' it."""
 
-        if state.committed_state is not None:
-            state.commit_attr(self, value)
+        state.commit_attr(self, value)
         # remove per-instance callable, if any
         state.callables.pop(self.key, None)
         state.dict[self.key] = value
@@ -395,7 +394,7 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl):
         if self.trackparent:
             if value is not None:
                 self.sethasparent(value._state, True)
-            if previous is not None:
+            if previous is not value and previous is not None:
                 self.sethasparent(previous._state, False)
 
         instance = state.obj()
@@ -544,7 +543,8 @@ class CollectionAttributeImpl(AttributeImpl):
         if old is value:
             return
 
-        state.committed_state[self.key] = self.copy(old)
+        if self.key not in state.committed_state:
+            state.committed_state[self.key] = self.copy(old)
 
         old_collection = self.get_collection(state, old)
 
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index b3b04b678..3dc7242d7 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -2815,7 +2815,7 @@ class _SelectBaseMixin(object):
         form of this method instead to prevent this issue.
         """
 
-        if clauses == [None]:
+        if len(clauses) == 1 and clauses[0] is None:
             self._order_by_clause = ClauseList()
         else:
             if getattr(self, '_order_by_clause', None):
@@ -2833,7 +2833,7 @@ class _SelectBaseMixin(object):
         form of this method instead to prevent this issue.
         """
 
-        if clauses == [None]:
+        if len(clauses) == 1 and clauses[0] is None:
             self._group_by_clause = ClauseList()
         else:
             if getattr(self, '_group_by_clause', None):