Fix installation error of same version of default gems with local installation

[hsbt]

What was the end-user or developer problem that led to this PR?

When we try to install local gem like pkg/bigdecimal-3.1.4.gem with Ruby 3.3.0-dev(ruby/ruby master version). RubyGems always fail with the following error.

https://github.com/ruby/bigdecimal/actions/runs/4269574995/jobs/7432842358

ERROR:  Error installing pkg/bigdecimal-3.1.4.gem:
	ERROR: Failed to build gem native extension.

    No such file or directory @ dir_s_mkdir - /home/runner/.rubies/ruby-head/lib/ruby/gems/3.3.0+0/gems/bigdecimal-3.1.4/ext/bigdecimal/.gem.2023022[5](https://github.com/ruby/bigdecimal/actions/runs/4269574995/jobs/7432842358#step:8:6)-1814-[6](https://github.com/ruby/bigdecimal/actions/runs/4269574995/jobs/7432842358#step:8:7)gtm34

Gem files will remain installed in /home/runner/.rubies/ruby-head/lib/ruby/gems/3.3.0+0/gems/bigdecimal-3.1.4 for inspection.
Results logged to /home/runner/.rubies/ruby-head/lib/ruby/gems/3.3.0+0/extensions/x[8](https://github.com/ruby/bigdecimal/actions/runs/4269574995/jobs/7432842358#step:8:9)6_64-linux/3.3.0+0/bigdecimal-3.1.4/gem_make.out

What is your fix for the problem, implemented in this PR?

This is too complex condition. The assumption is that json is default gems(bigdecimal-3.1.4 didn't release yet, I showed same example with json),
https://github.com/rubygems/rubygems/blob/master/lib/rubygems/request_set.rb#L183 is always true when it's given same name and same version.

When we try to install via rubygems.org like gem i json -v 2.6.3, It's working fine. When we use remote installation, gemspec is APISpecification in https://github.com/rubygems/rubygems/blob/master/lib/rubygems/request_set.rb#L184 like:

[Activation request
  [APISpecification name: json version: 2.6.3 platform: ruby dependencies: [] set uri: https://index.rubygems.org/info/]
   for [Dependency request  json (= 2.6.3)  requested by nil]]

This gemspec don't have Gem::Specificaiton#extensions like:

Gem::Specification.new do |s|
  s.name = "json"
  s.version = Gem::Version.new("2.6.3")
  s.installed_by_version = Gem::Version.new("0")
  s.authors = ["Florian Frank"]
  s.date = Time.utc(2022, 12, 5)
  s.description = "This is a JSON implementation as a Ruby extension in C."
  s.email = "flori@ping.de"
  s.homepage = "http://flori.github.com/json"
  s.metadata = {"bug_tracker_uri"=>"https://github.com/flori/json/issues",
   "changelog_uri"=>"https://github.com/flori/json/blob/master/CHANGES.md",
   "documentation_uri"=>"http://flori.github.io/json/doc/index.html",
   "homepage_uri"=>"http://flori.github.io/json/",
   "source_code_uri"=>"https://github.com/flori/json",
   "wiki_uri"=>"https://github.com/flori/json/wiki"}
  s.require_paths = ["lib"]
  s.required_ruby_version = Gem::Requirement.new([">= 2.3"])
  s.rubygems_version = "3.4.0.dev"
  s.specification_version = 4
  s.summary = "JSON Implementation for Ruby"
  end

Because https://github.com/rubygems/rubygems/blob/master/lib/rubygems/specification.rb#L1607 is skip to this Gem::Specification#build_extensions and download, build, install after that.

But when we invoke gem i pkg/json-2.6.3.gem, we have LocalSpecification like:

[Activation request
  [LocalSpecification name: json version: 2.6.3 platform: ruby dependencies: [] source: /Users/hsbt/Documents/github.com/flori/json/pkg/json-2.6.3.gem]
   for [Dependency request  json (= 2.6.3)  requested by nil]]

This gemspec have full spec of Gem::Specification:

Gem::Specification.new do |s|
  s.name = "json"
  s.version = Gem::Version.new("2.6.3")
  s.installed_by_version = Gem::Version.new("0")
  s.authors = ["Florian Frank"]
  s.date = Time.utc(2023, 3, 3)
  s.description = "This is a JSON implementation as a Ruby extension in C."
  s.email = "flori@ping.de"
  s.extensions = ["ext/json/ext/generator/extconf.rb", "ext/json/ext/parser/extconf.rb", "ext/json/extconf.rb"]
  s.extra_rdoc_files = ["README.md"]
  s.files = ["CHANGES.md",
   "LICENSE",
  # (snip)
   "lib/json/pure/parser.rb",
   "lib/json/version.rb"]
  s.homepage = "https://flori.github.io/json"
  s.licenses = ["Ruby"]
  s.metadata = {"bug_tracker_uri"=>"https://github.com/flori/json/issues",
   "changelog_uri"=>"https://github.com/flori/json/blob/master/CHANGES.md",
   "documentation_uri"=>"https://flori.github.io/json/doc/index.html",
   "homepage_uri"=>"https://flori.github.io/json",
   "source_code_uri"=>"https://github.com/flori/json",
   "wiki_uri"=>"https://github.com/flori/json/wiki"}
  s.rdoc_options = ["--title", "JSON implementation for Ruby", "--main", "README.md"]
  s.require_paths = ["/Users/hsbt/.local/share/gem/extensions/arm64-darwin-22/3.3.0+0-static/json-2.6.3", "lib"]
  s.required_ruby_version = Gem::Requirement.new([">= 2.3"])
  s.rubygems_version = "3.5.0.dev"
  s.specification_version = 4
  s.summary = "JSON Implementation for Ruby"
end

So, Gem::Specification#build_extensions try to build this spec despite there is no files of json-2.6.3.

---

I added guard condition to Gem::Specification#build_extensions for fullname of default gems.

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

[deivid-rodriguez]

Is this related to #6429?

[hsbt]

Yes. But I think #6429 is correct behavior with current implementation. I fixed only broken behavior of C-ext gem and local installation. So, pure ruby gem, C-ext gem and remote installation are working fine.

We can consider skipping all of gem installation with same default gems version after this.

[hsbt]

Ah, I only said a target gem like foo of gem install foo. If #6429 said "Do not fetch dependencies that are default gems", It may be bug of rubygems.

I'm not sure this PR fix #6429 yet.