Make identical products return the same type

[cdonovick]

Resolves #76

[rdaly525]

@cdonovick, this breaks lassen. I am trying to investigate, but it is definitely when trying to generate magma.

EDIT:
definitely incompatible with the way that magma is doing Product

@leonardt

import magma as m
class A(m.Product):
  a=m.Bit
#the above raises an error in ProductMeta._from_fields

[leonardt]

@rdaly525 this might be fixed by phanrahan/magma@57dc066, can you try it with the latest magma master/release?

[rdaly525]

Getting a different error now! so closer...

Error from above code:

  File "/Users/rdaly/hwtypes/hwtypes/adt_meta.py", line 241, in __new__
    return mcs._from_fields(fields, name, bases, ns, cache, **kwargs)
TypeError: _from_fields() takes 5 positional arguments but 6 were given

[leonardt]

Ah, looks like that interface changed, I'll open a magma PR with the update.

[leonardt]

PR is here: phanrahan/magma#427, running the lassen test suite now, seems to be making good progress

[rdaly525]

@leonardt once that PR is in, the GarnetFlow should be fixed for this PR

[rdaly525]

@cdonovick Can you add the exact test from #74? Other than that looks good.

[cdonovick]

Now also resolves #74