Maxima 5.26.0 http://maxima.sourceforge.net
using Lisp SBCL 1.0.24
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%o1) /Users/.../maxima-5.26.0/share/contrib/solve_re\ c/simplify_sum.mac
(%o2) - log(2)
(%o3) - log(2)
You'll notice that the second sum would have 1/0 as a term, though.
Originally reported by dkrenn at http://trac.sagemath.org/sage_trac/ticket/12410.