Merge pull request #1721 from npbaskerville/master

Swithed to tensor all method to avoid errors when using pyro samples.

Author: jacobrgardner

gpytorch/lazy/root_lazy_tensor.py

@@ -56,7 +56,7 @@ def _matmul(self, rhs):
         return self.root._matmul(self.root._t_matmul(rhs))
 
     def _mul_constant(self, constant):
-        if constant > 0:
+        if (constant > 0).all():
             res = self.__class__(self.root._mul_constant(constant.sqrt()))
         else:
             res = super()._mul_constant(constant)