Deprecated transformations?

[Bill Hart]

Here's a synopsis of a Pyomo issue I'd like to get feedback on.  It'd be best to comment on the ticket, but I'm reproducing it here to solicit input:  https://github.com/Pyomo/pyomo/issues/273

The following model transformations are either weakly tested or not tested at all:

core.radix_linearization

core.remove_fixed_vars

core.nonnegative_vars

Each of these transformations perform nontrivial changes of the expression tree, and hence they should be reworked to use the new expression tree walker that has been developed on the expr_dev branch. But the fact that these are so poorly tested suggests that they are not used in practice.

Should we keep these transformations?  Can you point to examples where they are being used?