It is not possible to generate todo file in a subdirectory

[Ana06]

I have the following

root
  -> .rubocop.yml
  -> .rubocop_todo.yml
  -> directory
     -> .rubocop.yml

The content of directory/.rubocop.yml is:

inherit_from: ../.rubocop.yml

Running rubocop --auto-gen-config inside the directory fails:

> rubocop --auto-gen-config
(.rubocop.yml): could not find expected ':' while scanning a simple key at line 5 column 1
/usr/lib64/ruby/2.5.0/psych.rb:402:in `parse'
/usr/lib64/ruby/2.5.0/psych.rb:402:in `parse_stream'
/usr/lib64/ruby/2.5.0/psych.rb:350:in `parse'
/usr/lib64/ruby/2.5.0/psych.rb:314:in `safe_load'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/config_loader.rb:184:in `yaml_safe_load'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/config_loader.rb:157:in `load_yaml_configuration'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/config_loader.rb:130:in `add_inheritance_from_auto_generated_file'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/cli.rb:125:in `reset_config_and_auto_gen_file'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/cli.rb:77:in `execute_runners'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/lib/rubocop/cli.rb:41:in `run'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/exe/rubocop:13:in `block in <top (required)>'
/usr/lib64/ruby/2.5.0/benchmark.rb:308:in `realtime'
/usr/lib64/ruby/gems/2.5.0/gems/rubocop-0.57.1/exe/rubocop:12:in `<top (required)>'
/usr/local/bin/rubocop:23:in `load'
/usr/local/bin/rubocop:23:in `<main>'

The content of directory/.rubocop.yml after running the command is:

inherit_from:
  - .rubocop_todo.yml
  - ../.rubocop.yml

/.rubocop.yml

If I change the content of directory/.rubocop.yml to

inherit_from:
  - .rubocop_todo.yml
  - ../.rubocop.yml

then it works as expected, but I think that the first case should work as well.

RuboCop version

0.57.1 (using Parser 2.5.1.0, running on ruby 2.5.0 x86_64-linux-gnu)