fix for expt bug

[Ramakrishnan Muthukrishnan]

Hi,

As reported here:

<https://savannah.gnu.org/bugs/index.php?31464>

expt currently wrongly prints the results for any negative base
numbers. The attached patch (also attached with the bug tracker) has a
fix and also adds a test case.

This is my first patch to guile, so please correct me if I have done
something wrong. I will be happy to rework it. I am yet to recieve the
assignment papers from the FSF (but they have been despatched already
by the FSF), I will mail them back as soon as I get it.

thanks
-- 
  Ramakrishnan

expt-fix.patch
Description: Text Data