ack 2.18 will probably be the final release in the ack 2.x series. I'm going to be starting work on ack 3.000 in earnest. Still, if you discover problems with ack 2, please report them to https://github.com/petdance/ack2/issues
If you're interested in ack 3 development, please sign up for the ack-dev mailing list and/or join the ack Slack. See https://beyondgrep.com/community/ for details.
INTERNALS
Removed the abstraction of App::Ack::Resource and its subclass App::Ack::Resource::Basic. We are abandoning the idea that we'll have plugins.
Changes for version 2.17_02 - 2017-03-23
FIXES
ack no longer throws an undefined variable warning if it's called from a directory that doesn't exist. (GH #634)
DOCUMENTATION
Explain that filetypes must be two characters or longer. (GH #389)
INTERNALS
Removed dependency on File::Glob which isn't used.
Changes for version 2.17_01 - 2017-03-15
FIXES
--context=0 (and its short counterpart -C 0) did not set to context of 0. This means that a command-line --context=0 couldn't override a --context=5 in your ackrc. Thanks, Ed Avis. (GH #595)
t/ack-s.t would fail in non-English locales. Thanks, Olivier Mengué. (GH #485, GH #515)
ENHANCEMENTS
--after-context and --before-context (and their short counterparts -A and -B) no longer require a value to be passed. If no value is set, they default to 2. (GH #351)
Added .xhtml to the --html filetype. Added .wsdl to the --xml filetype. Thanks, H.Merijn Brand. (GH #456)
DOCUMENTATION
Updated incorrect docs about how ack works. Thanks, Gerhard Poul. (GH #543)