Stop loading resolv from net/http

[hsbt]

require 'net/http' loads all of resolv, a DNS resolver of about 3,700 lines that also reads the system DNS configuration at load time. Net::HTTP#connect uses it only for Resolv::IPv4::Regex and Resolv::IPv6::Regex, to decide whether to send SNI.

I copied the regexps that the net-http vendored in RubyGems already inlines (ruby/rubygems@9f2bd5f66c), so the two copies stay identical. They accept the same strings as the resolv ones over 6 million generated inputs. A new test checks that net/http no longer defines Resolv.

Code that uses Resolv or SecureRandom after requiring only net/http now needs its own require. Nothing in this repository relies on that. A few gems on rubygems.org use Resolv that way, such as firespring_dev_commands.

Generated with Claude Code

[github-actions]

The following files are maintained in the following upstream repositories:

• https://github.com/ruby/net-http
  • lib/net/http.rb
  • test/net/http/test_http.rb

Please file a pull request to the above instead. Thank you!

[hsbt]

Superseded by 6095c59, which synced the same change from ruby/net-http#355.