Properly handle incompatibilities on platform specific gems

[deivid-rodriguez]

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

When creating incompatibilities for requirements with no matching versions here:

rubygems/bundler/lib/bundler/resolver.rb

Lines 154 to 176 in 9abd8ac

	def no_versions_incompatibility_for(package, unsatisfied_term)
	cause = PubGrub::Incompatibility::NoVersions.new(unsatisfied_term)
	name = package.name
	constraint = unsatisfied_term.constraint
	constraint_string = constraint.constraint_string
	requirements = constraint_string.split(" OR ").map {|req| Gem::Requirement.new(req.split(",")) }
	if name == "bundler"
	custom_explanation = "the current Bundler version (#{Bundler::VERSION}) does not satisfy #{constraint}"
	extended_explanation = bundler_not_found_message(requirements)
	else
	specs_matching_other_platforms = filter_matching_specs(@all_specs[name], requirements)
	platforms_explanation = specs_matching_other_platforms.any? ? " for any resolution platforms (#{package.platforms.join(", ")})" : ""
	custom_explanation = "#{constraint} could not be found in #{repository_for(package)}#{platforms_explanation}"
	label = "#{name} (#{constraint_string})"
	extended_explanation = other_specs_matching_message(specs_matching_other_platforms, label) if specs_matching_other_platforms.any?
	end
	Incompatibility.new([unsatisfied_term], :cause => cause, :custom_explanation => custom_explanation, :extended_explanation => extended_explanation)
	end

We receive a pub grub version range, and need to convert it to a "standard" requirement. We parse the string representation of the version range for that. However, if the version range includes platform specific candidates, those were include the platform under parenthesis, making the string representation unparseable.

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

To fix the bug, we use only the string representation of the underlying version as the string representation of a candidate. Error messages already include the resolution platforms separately so it should not degrade with end users see or make any messages less clear.

Fixes #6267.

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

[simi]

ℹ️ btw. good case to utilize "hide whitespace" on "Files changed" tab for easy review.

[deivid-rodriguez]

Yay!