Fix imports necessary to run DirichletMultinomial sampling. (#1275)

Author: bsmith89

pymc3/tuning/scaling.py

@@ -7,7 +7,8 @@
 import numpy as np
 from numpy import exp, log, sqrt
 from ..model import modelcontext, Point
-from ..theanof import hessian_diag
+from ..theanof import hessian_diag, inputvars
+from ..blocking import DictToArrayBijection, ArrayOrdering
 
 __all__ = ['approx_hessian', 'find_hessian', 'trace_cov', 'guess_scaling']