small fix following review

theano/gof/fg.py

@@ -268,7 +268,7 @@ class FunctionGraph(utils.object2):
         r
             Variable.
         new_client
-            (node, i) pairs such that node.inputs[i] is r.
+            (node, i) pair such that node.inputs[i] is r.
 
         """
         # Ne need to do the assert as it is always True. The logic
@@ -293,8 +293,8 @@ class FunctionGraph(utils.object2):
         ----------
         r : Variable
             The clients of r will be removed.
-        client_to_remove : (op, i) pairs
-            (op, i) pairs such that node.inputs[i] is not r anymore.
+        client_to_remove : (op, i) pair
+            (op, i) pair such that node.inputs[i] is not r anymore.
         prune : bool
             If prune is True, it remove r from this fgraph if it don't
             have clients left.

theano/gpuarray/opt.py

@@ -299,7 +299,6 @@ class GraphToGPU(Optimizer):
         # Iterating through inputs of graph
         target = infer_context_name(*fgraph.inputs)
         for i in fgraph.inputs:
-            # Do not move *int* scalar to the GPU.
             if isinstance(i.type, tensor.TensorType) and move_to_gpu(i):
                 mapping[i] = i.transfer(getattr(i.tag, 'target', target))
             else:

theano/gpuarray/type.py

@@ -581,25 +581,33 @@ class GpuArraySharedVariable(_operators, SharedVariable):
 
 
 GpuArrayType.SharedVariable = GpuArraySharedVariable
+notset = object()
 
 
 def gpuarray_shared_constructor(value, name=None, strict=False,
                                 allow_downcast=None, borrow=False,
-                                broadcastable=None, target=None):
+                                broadcastable=None, target=notset):
     """
     SharedVariable constructor for GpuArrayType.
 
     See :func:`theano.shared`.
 
+    :target: default None
+        The device target. As None is a valid value and we need to
+        differentiate from the parameter notset and None, we use a
+        notset object.
+
     """
-    if target is None and not move_to_gpu(value):
-        raise TypeError('We do not move that data by deault to the GPU')
     if target == 'gpu' or target == 'cpu':
         raise TypeError('not for me')
 
     if not isinstance(value, (numpy.ndarray, pygpu.gpuarray.GpuArray)):
         raise TypeError('ndarray or GpuArray required')
 
+    if target is notset:
+        target = None
+        if not move_to_gpu(value):
+            raise TypeError('We do not move that data by default to the GPU')
     try:
         get_context(target)
     except ContextNotDefined: