segfault in mpz_divexact()

[Torbjorn Granlund]

I have now reproduced the SIGSEGV.  (You seem to have grown impatient
after less than a day, but since you don't have a support contract, I
hope you can excuse a delay of a full day...?)

I need to think about what to do--document more clearly that the
function's behaviour is undefined when the division is inexact, or add
code and thus overhead to the function to catch this user error.

(The documentation of this function could be clarified in other ways.
E.g., that one should never call this function if one first need to
verify that the remainder vanishes.)

-- 
Torbjörn