fix trivial doctest failure
Trac #15582: Update to Gap 4.7.2

New tarballs:

* http://boxen.math.washington.edu/home/release/sage-6.1.beta3/upstream/
gap-4.7.2.tar.bz2
* http://boxen.math.washington.edu/home/release/sage-6.1.beta3/upstream/
gap_packages-4.7.2.tar.bz2
* http://boxen.math.washington.edu/home/release/sage-6.1.beta3/upstream/
database_gap-4.7.2.tar.bz2
* http://boxen.math.washington.edu/home/release/sage-6.1.beta3/upstream/
libgap-4.7.2.tar.gz

URL: http://trac.sagemath.org/15582
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): Travis Scrimshaw