shuffle (and infiltrate) does not work with denormalized expansions
Try this:
vcsn.context('lan, q').expression('((⟨2⟩ε){\}a) : b').automaton()
vcsn.context('lan, q').expression('((⟨2⟩ε){\}a) : b').inductive()
The first one is wrong, the second one is right.
When both #86 and #87 are fixed, restore the commented tests about check_prod in tests/python/to-expansion.py
.