#3390 ?great mishandles box

[Stavros Macrakis]

?great(box(x+t),-box(x+t)) => true
?great(-box(x+t),box(x+t)) => true

It should never be true that ?great(x,y)=?great(y,x)=true if x#y

This bug causes the following bug:
sin(box(x+t)) => stack overflow

The solution (for now at least) is to remove these two lines from great:

((member (caar x) '(mbox mlabox) :test #'eq) (great (cadr x) y))
((member (caar y) '(mbox mlabox) :test #'eq) (great x (cadr y)))

If I remember correctly, I added those lines a long time ago thinking it was trivially obvious that they were correct. :-(

This also fixes bug 2012 Lisp stack overflow with dpart

[Robert Dodier]

I've applied the bug fix as commit 1aec495. Closing this report as fixed.