old_contents: import os
  import copy
  import os
  
  import yaml
  
  
  def load_overrides(root, *, environ=None):
      if environ is None:
          environ = os.environ
      config_dir = environ.get('COB_CONFIG_DIR')
      if config_dir is not None and os.path.isdir(config_dir):
          for yaml_file in sorted(os.listdir(config_dir)):
              with open(os.path.join(config_dir, yaml_file)) as f:
                  root = merge_config(root, yaml.load(f))
      return root
  
  def merge_config(parent, *children):
      returned = copy.deepcopy(parent)
      for child in children:
          for key, value in child.items():
              if isinstance(value, dict):
                  if key not in returned:
                      returned[key] = value.copy()
                  else:
                      if not isinstance(returned[key], dict):
                          raise ValueError('Cannot merge dictionaries: value of {!r} is not a dictionary'.format(key))
                      returned[key].update(value)
              else:
                  returned[key] = copy.deepcopy(value)
      return returned
  
new_contents: import copy
  import os
  
  import yaml
  
  
  def load_overrides(root, *, environ=None):
      if environ is None:
          environ = os.environ
      config_dir = environ.get('COB_CONFIG_DIR')
      if config_dir is not None and os.path.isdir(config_dir):
          for yaml_file in sorted(os.listdir(config_dir)):
              with open(os.path.join(config_dir, yaml_file)) as f:
                  root = merge_config(root, yaml.load(f))
      return root
  
  def merge_config(parent, *children):
      returned = copy.deepcopy(parent)
      for child in children:
          for key, value in child.items():
              if isinstance(value, dict):
                  if key not in returned:
                      returned[key] = value.copy()
                  else:
                      if not isinstance(returned[key], dict):
                          raise ValueError('Cannot merge dictionaries: value of {!r} is not a dictionary'.format(key))
                      returned[key].update(value)
              else:
                  returned[key] = copy.deepcopy(value)
      return returned
  
subject: fix pylint warning