Execution throws if a Kernel Variable is set to CONSTANT

[pabfer]

Describe the bug

If a kernel Variable is of CONSTANT type, fetch_parameters throws here since CONSTANT Variables do not make it to params input argument.

Expected behavior

Execution does not throw, and kernel Variables that are of type CONSTANT are kept constant and not optimized in training.

Desktop:

• OS: Ubuntu 18.04.2
• Python version: 3.6
• MXNet version: 1.4.1
• MXFusion version: 0.3.1
• MXNet context: CPU

[meissnereric]

Thanks for filing this!

Not sure exactly where the fix is here, but after a little digging I would guess that the kernel constants parameters just aren't making it into the variables with the rest of the constants during Inference initialization. Shouldn't be a hard thing to fix once we find it.