The following script makes it a no-brainer:
% NEXT_YEAR=2015; ag -l 'Copyright.*Wiegley' \
| xargs sed -i '' -e "s/\(Copyright.*\)-20[0-9]\{2\}/\1-${NEXT_YEAR}/"
As the format used by property trees to represent valid JSON
and that for valid XML is too different and given that there are
more requests for valid XML output I decided to pursue a quick fix
and remove the json command in favor of a working xml command.
See bug #782, #909, recent discussion on mailing list.
JSON support is postponed until I or someone else finds time to work on
this or the python bindings are more stable.
