Remove unused kconv require

[deepj]

It seems to be require 'kconv' (Kanji converter in the standard Ruby libraries) is not used anywhere at all.

This found in truffle-ruby which hasn't been kconv yet in this issue oracle/truffleruby#1439

This thing was introduced in this commit 5c8e802

[eregon]

The CI seems to reveal that mechanize doesn't seem to use the kconv library itself, but ntlm-http 0.1.1 does:

  1) Error:
TestMechanizeHttpAgent#test_response_authenticate_ntlm:
NameError: uninitialized constant Module::Kconv
    /home/travis/.rvm/gems/ruby-2.2.7/gems/ntlm-http-0.1.1/lib/net/ntlm.rb:103:in `encode_utf16le'

That seems a pretty old gem, and I can't find the source repository easily.
That gem should of course take care of require-ing its own dependencies, but somehow does not.

The source from the unpacked gem looks like:

      def encode_utf16le(str)
        swap16(Kconv.kconv(str, Kconv::UTF16, Kconv::ASCII))
      end
      
      def swap16(str)
        str.unpack("v*").pack("n*")
      end

That might maybe be simplified by using String#encode nowadays, but I'm not sure of the semantics of kconv.

On the mechanize side, it looks like the ntlm-http dependency could be lazily loaded in

mechanize/lib/mechanize/http/agent.rb

Line 781 in b959fb1

type_2 = Net::NTLM::Message.decode64 challenge.params

Which would avoid requiring both ntlm-http and kconv eagerly.

What do the mechanize authors think?

But at this point I of course realize Ruby implementations should just support kconv since it's a standard library still distributed in latest MRI.

[deepj]

@eregon https://rubygems.org/gems/ntlm-http the last version (and only one) was released almost 10 years ago, and it seems it won't be fixed. Alternatively, mechanize can use a different library for NTLM support though.

[flavorjones]

Related: #565

[flavorjones]

I've rebased this off master to ensure CI runs.

[flavorjones]

Possibly related: #574 removed the dependency on ntlm-http and replaced it with rubyntlm. Rebasing now to see what CI thinks.

[deepj]

@flavorjones it looks good! :)

[flavorjones]

Will be in the next release, v2.8.0