optdb - added constant merge between canonicalize and stabilize to fix bug in SdA

theano/compile/mode.py

@@ -131,7 +131,7 @@ optdb.register('merge1', gof.MergeOptimizer(),
         0, 'fast_run', 'fast_compile')
 optdb.register('canonicalize', gof.EquilibriumDB(),         # rearranges elemwise expressions
         1, 'fast_run')
-optdb.register('merge1.2', gof.MergeOptimizer(skip_const_merge=True),
+optdb.register('merge1.2', gof.MergeOptimizer(skip_const_merge=False),
         1.2, 'fast_run', 'fast_compile')
 optdb.register('stabilize', gof.EquilibriumDB(),            # replace unstable subgraphs
         1.5, 'fast_run')