Fix problem with eager loading polymorphic associations in mongoid 9

[danarnold]

Fixes #22

[Copilot]

Pull Request Overview

This PR fixes a problem with eager loading polymorphic associations in Mongoid 9 by addressing object mutation issues when cloning relation metadata. The fix ensures that options are properly duplicated to prevent unintended side effects when handling multiple concrete types in polymorphic relationships.

• Adds defensive copying of options hash when cloning relation metadata for polymorphic associations
• Includes comprehensive test coverage for multiple concrete types and CLI reproduction scenarios
• Addresses issue #22 related to polymorphic association eager loading failures

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
lib/mongoid/includes/inclusion.rb	Adds @options = @options.dup to prevent mutation of shared options hash when cloning metadata
spec/mongoid/includes/polymorphic_includes_spec.rb	Adds extensive test coverage for polymorphic eager loading with multiple concrete types and CLI reproduction

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[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[danarnold]

@jclusso I merged your PR. Can't re-request review.