Post-install message from rubyzip:
RubyZip 3.0 is coming!
**********************
The public API of some Rubyzip classes has been modernized to use named
parameters for optional arguments. Please check your usage of the
following classes:
* `Zip::File`
* `Zip::Entry`
* `Zip::InputStream`
* `Zip::OutputStream`
Please ensure that your Gemfiles and .gemspecs are suitably restrictive
to avoid an unexpected breakage when 3.0 is released (e.g. ~> 2.3.0).
See https://github.com/rubyzip/rubyzip for details. The Changelog also
lists other enhancements and bugfixes that have been implemented since
version 2.3.0.
rubyzipが何か変わる模様。