[issue19018] Heapq.merge suppreses IndexError from user generator

[Artem Fokin]

Changes by Artem Fokin <ar.fokin at gmail.com>:


----------
versions:  -3rd party, Python 2.6, Python 3.4, Python 3.5

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue19018>
_______________________________________