- Change in TcSimplify.reduceContext:

     We do *not* go around for new extra_eqs.  Morally, we should,
     but we can't without risking non-termination (see #2688).  By
     not going around, we miss some legal programs mixing FDs and
     TFs, but we never claimed to support such programs in the
     current implementation anyway.

  MERGE TO 6.10