TensorType - make sure that broadcastable is a tuple of bools

theano/tensor/basic.py

@@ -331,7 +331,8 @@ class TensorType(Type):
         self.dtype = str(dtype)
         if self.dtype=='floatX':
           self.dtype=config.floatX
-        self.broadcastable = tuple(broadcastable)
+        ###    broadcastable is immutable, and all elements are either True or False
+        self.broadcastable = tuple(bool(b) for b in broadcastable) 
         self.dtype_specs() # error checking is done there
         self.name = name
         self.numpy_dtype = numpy.dtype(self.dtype)