More uniform handling of variable patterns in Btermdn.
More uniform handling of variable patterns in Btermdn.

We first check that a pattern variable has a body before looking it up in the
transparent state. This only affects discriminated nets. The behaviour or
non-discriminated nets is very weird and asymmetrical since in patterns variables
match everything but in terms they match only variables, regardless of the existence
of a body.

SkySkimmer/coq,SkySkimmer/coq,Zimmi48/coq,coq/coq,SkySkimmer/coq,ejgallego/coq,coq/coq,coq/coq,Zimmi48/coq,ejgallego/coq,ejgallego/coq,SkySkimmer/coq,Zimmi48/coq,coq/coq,ejgallego/coq,Zimmi48/coq