Fixed bug where list instrumentation would fail to represent a

setslice of ``[0:0]`` correctly, which in particular could occur
when using ``insert(0, item)`` with the association proxy.  Due
to some quirk in Python collections, the issue was much more likely
with Python 3 rather than 2.  Also in 0.8.3, 0.7.11.
[ticket:2807]

5 files changed, 42 insertions, 4 deletions

diff --git a/doc/build/changelog/changelog_07.rst b/doc/build/changelog/changelog_07.rst
index c6da742b8..be1dd9891 100644
--- a/doc/build/changelog/changelog_07.rst
+++ b/doc/build/changelog/changelog_07.rst
@@ -7,6 +7,16 @@
     :version: 0.7.11
 
     .. change::
+        :tags: bug, orm
+        :tickets: 2807
+
+        Fixed bug where list instrumentation would fail to represent a
+        setslice of ``[0:0]`` correctly, which in particular could occur
+        when using ``insert(0, item)`` with the association proxy.  Due
+        to some quirk in Python collections, the issue was much more likely
+        with Python 3 rather than 2.
+
+    .. change::
         :tags: bug, sql
         :tickets: 2801
 
diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index c19fa2227..39a8627ba 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -8,6 +8,16 @@
 
     .. change::
         :tags: bug, orm
+        :tickets: 2807
+
+        Fixed bug where list instrumentation would fail to represent a
+        setslice of ``[0:0]`` correctly, which in particular could occur
+        when using ``insert(0, item)`` with the association proxy.  Due
+        to some quirk in Python collections, the issue was much more likely
+        with Python 3 rather than 2.  Also in 0.7.11.
+
+    .. change::
+        :tags: bug, orm
         :tickets: 2779
 
         Backported a change from 0.9 whereby the iteration of a hierarchy
diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst
index 3c38367f2..d928120f9 100644
--- a/doc/build/changelog/changelog_09.rst
+++ b/doc/build/changelog/changelog_09.rst
@@ -8,6 +8,16 @@
 
     .. change::
         :tags: bug, orm
+        :tickets: 2807
+
+        Fixed bug where list instrumentation would fail to represent a
+        setslice of ``[0:0]`` correctly, which in particular could occur
+        when using ``insert(0, item)`` with the association proxy.  Due
+        to some quirk in Python collections, the issue was much more likely
+        with Python 3 rather than 2.  Also in 0.8.3, 0.7.11.
+
+    .. change::
+        :tags: bug, orm
         :tickets: 2794
 
         Fixed a potential issue in an ordered sequence implementation used
diff --git a/lib/sqlalchemy/orm/collections.py b/lib/sqlalchemy/orm/collections.py
index f8f4b9583..6bd5ac968 100644
--- a/lib/sqlalchemy/orm/collections.py
+++ b/lib/sqlalchemy/orm/collections.py
@@ -1075,7 +1075,10 @@ def _list_decorators():
                 start = index.start or 0
                 if start < 0:
                     start += len(self)
-                stop = index.stop or len(self)
+                if index.stop is not None:
+                    stop = index.stop
+                else:
+                    stop = len(self)
                 if stop < 0:
                     stop += len(self)
 
diff --git a/test/orm/test_collection.py b/test/orm/test_collection.py
index 3a98da90f..4eb8b3fee 100644
--- a/test/orm/test_collection.py
+++ b/test/orm/test_collection.py
@@ -128,9 +128,9 @@ class CollectionsTest(fixtures.ORMTest):
         control = list()
 
         def assert_eq():
-            self.assert_(set(direct) == canary.data)
-            self.assert_(set(adapter) == canary.data)
-            self.assert_(direct == control)
+            eq_(set(direct), canary.data)
+            eq_(set(adapter), canary.data)
+            eq_(direct, control)
 
         # assume append() is available for list tests
         e = creator()
@@ -260,6 +260,11 @@ class CollectionsTest(fixtures.ORMTest):
             control[-2:-1] = values
             assert_eq()
 
+            values = [creator()]
+            direct[0:0] = values
+            control[0:0] = values
+            assert_eq()
+
 
         if hasattr(direct, '__delitem__') or hasattr(direct, '__delslice__'):
             for i in range(1, 4):