ActiveRecord::HasManyThroughCantAssociateThroughHasManyReflection being thrown when calling destroy_all on a :has_many :through association

As of this commit, calling destroy_all on a :has_many :through association raises an ActiveRecord::HasManyThroughCantAssociateThroughHasManyReflection exception. This wasn't the case before this commit.

e.g. Given:

class Company
  has_many :projects, :through => :contacts
end

Calling company.projects.destroy_all results in:

ActiveRecord::HasManyThroughCantAssociateThroughHasManyReflection: Cannot modify association 'MyClass#projects' because the source reflection class 'Project' is associated to 'Contact' via :has_many

Calling company.projects.all.destroy_all works, however.