Remove duplicate sample_except()

Author: gmingas

pymc3/step_methods/metropolis.py

@@ -880,13 +880,6 @@ def competence(var, has_grad):
         return Competence.COMPATIBLE
 
 
-def sample_except(limit, excluded):
-    candidate = nr.choice(limit - 1)
-    if candidate >= excluded:
-        candidate += 1
-    return candidate
-
-
 class MLDA(ArrayStepShared):
     """
     Multi-Level Delayed Acceptance (MLDA) sampling step that uses coarse