Recently a changed was introduced to update the resolver platforms after it has been created, in order to remove the "ruby" platform from it if it's to be removed from the lockfile. However, it did not update the `@resolving_only_for_ruby` instance variable in that case, so the resolver was not properly doing the right thing anymore. To fix this, I tweaked the code to restore not changing resolver platforms after the resolver has been instantiated. https://github.com/rubygems/rubygems/commit/8fbc30a1d0