Positional argument fix for DiscreteBound

Author: sshekh

pymc3/distributions/bound.py

@@ -103,8 +103,8 @@ def __init__(self, distribution, lower, upper,
             default = lower + 1
 
         super().__init__(
-            distribution=distribution, lower=lower, upper=upper,
-            default=default, *args, **kwargs)
+            distribution, lower, upper,
+            default, *args, transform=transform, **kwargs)
 
 
 class _ContinuousBounded(_Bounded, Continuous):

pymc3/tests/test_distributions.py

@@ -1300,6 +1300,11 @@ def test_bound():
         BoundNormalPositionalArgs = Bound(Normal, upper=6)("x", 2., 1.)
 
 
+    with Model():
+        BoundPoissonNamedArgs = Bound(Poisson, upper=6)("y", mu=2.)
+        BoundPoissonPositionalArgs = Bound(Poisson, upper=6)("x", 2.)
+
+
 class TestLatex:
 
     def setup_class(self):