concurrent-ruby 1.2.0 breaks puppet

Puppet Version: 7.x
Puppet Server Version: N/A
OS Name/Version: N/A

concurrent-ruby 1.2.0 was just released and breaks running Puppet using gem/bundler.

It looks like puppet use a private class of this gem that got removed in:

https://github.com/ruby-concurrency/concurrent-ruby/commit/30465396414e13290c3e1d8d26a0f2de2ebedc4c

Desired Behavior:

Puppet should work with concurrent-ruby 1.2.0

Actual Behavior:

romain@zappy ~/Projects/puppetlabs % git clone git@github.com:puppetlabs/puppet.git
romain@zappy ~/Projects/puppetlabs % cd puppet
romain@zappy ~/Projects/puppetlabs/puppet % bundle install
romain@zappy ~/Projects/puppetlabs/puppet % bundle show concurrent-ruby
/usr/home/romain/.vendor/ruby/3.0/gems/concurrent-ruby-1.2.0
romain@zappy ~/Projects/puppetlabs/puppet % bundle exec bin/puppet
bundler: failed to load command: bin/puppet (bin/puppet)
/usr/home/romain/Projects/puppetlabs/puppet/lib/puppet/thread_local.rb:6:in `<top (required)>': uninitialized constant Concurrent::RubyThreadLocalVar (NameError)
Did you mean?  Concurrent::RubyThreadPoolExecutor
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet/context.rb:1:in `require_relative'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet/context.rb:1:in `<top (required)>'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet.rb:45:in `require_relative'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet.rb:45:in `<module:Puppet>'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet.rb:42:in `<top (required)>'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet/util/command_line.rb:12:in `require_relative'
    from /usr/home/romain/Projects/puppetlabs/puppet/lib/puppet/util/command_line.rb:12:in `<top (required)>'
    from bin/puppet:4:in `require'
    from bin/puppet:4:in `<top (required)>'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli/exec.rb:58:in `load'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli/exec.rb:58:in `kernel_load'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli/exec.rb:23:in `run'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli.rb:483:in `exec'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli.rb:31:in `dispatch'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/cli.rb:25:in `start'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/exe/bundle:48:in `block in <top (required)>'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/lib/bundler/friendly_errors.rb:103:in `with_friendly_errors'
    from /usr/home/romain/.vendor/ruby/3.0/gems/bundler-2.3.12/exe/bundle:36:in `<top (required)>'
    from /usr/local/bin/bundle:25:in `load'
    from /usr/local/bin/bundle:25:in `<main>'

Workaround:

Add this line to the Gemfile to use the previous version of concurrent-ruby :

gem 'concurrent-ruby', '< 1.2.0'