[toolsutils] Small fixes to fill_templated_file() * Use context managers to close _both_ files * Use io.open to enforce text mode on both python 2 and 3

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
http://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))