Fixed two bugs in copyprop.

src/optimize/__init__.py

@@ -3,7 +3,8 @@ from dataflow import find_basic_blocks
 from standard import redundant_move_1, redundant_move_2, \
         redundant_move_3, redundant_move_4, redundant_load, \
         redundant_shift, redundant_add
-from advanced import eliminate_common_subexpressions, fold_constants
+from advanced import eliminate_common_subexpressions, fold_constants, \
+    copy_propagation
 
 
 def optimize_global(statements):

src/optimize/advanced.py

@@ -108,4 +108,4 @@ def copy_propagation(block):
             count += 1
             
     print "count", count
-    return false
+    return False