I've just uploaded ack 2.18 to CPAN and to https://beyondgrep.com/. 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. 
2.18    Fri Mar 24 14:53:19 CDT 2017
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[FIXES]
ack no longer throws an undefined variable warning if it's called
from a directory that doesn't exist. (GH #634)

--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]
Explain that filetypes must be two characters or longer. (GH #389)

Updated incorrect docs about how ack works.  Thanks, Gerhard Poul.
(GH #543)

[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.

Removed dependency on File::Glob which isn't used.