Misc compatibility fixes

src/runtime/list.cpp

@@ -786,7 +786,8 @@ Box* listIAdd(BoxedList* self, Box* _rhs) {
 }
 
 Box* listAdd(BoxedList* self, Box* _rhs) {
-    if (_rhs->cls != list_cls) {
+    if (!PyList_Check(_rhs)) {
+        return NotImplemented;
         raiseExcHelper(TypeError, "can only concatenate list (not \"%s\") to list", getTypeName(_rhs));
     }
 

src/runtime/types.cpp

@@ -3864,6 +3864,7 @@ void setupRuntime() {
 
     none_cls->giveAttr("__repr__", new BoxedFunction(boxRTFunction((void*)noneRepr, STR, 1)));
     none_cls->giveAttr("__nonzero__", new BoxedFunction(boxRTFunction((void*)noneNonzero, BOXED_BOOL, 1)));
+    none_cls->giveAttr("__doc__", None);
     none_cls->tp_hash = (hashfunc)_Py_HashPointer;
     none_cls->freeze();
 

test/tests/list_subclassing.py

@@ -39,6 +39,8 @@ print MyList((1,2,3)) <= MyList((1,2,3))
 
 print type(MyList((1, 2, 3)) * 1)
 
+print [1] + MyList([3])
+
 class ListWithInit(list):
     def __init__(self, *args, **kwargs):
         print "ListWithInit.__init__", args, kwargs

test/tests/none__class__.py

 print None.__class__
+
+print type(None).__doc__, None.__doc__

test/tests/str_adding.py

@@ -18,3 +18,7 @@ try:
 except TypeError as e:
     print e
 print "" + D()
+
+
+# This also applies to list:
+print [] + D()

test/tests/str_adding_compat.py

@@ -7,3 +7,8 @@ try:
     print "".__add__(1)
 except TypeError as e:
     print e
+
+try:
+    print [].__add__(1)
+except TypeError as e:
+    print e