old_contents: class MissingRemote(Exception):
  
      """
      Raise when a remote by name is not found.
  
      """
      pass
  
  
  class MissingMasterBranch(Exception):
  
      """
      Raise when the "master" branch cannot be located.
  
      """
      pass
  
  
  class BaseOperation(object):
  
      """
      Base class for all Git-related operations.
  
      """
      def __init__(self, repo, remote_name='origin', master_branch='master'):
          self.repo = repo
          self.remote_name = remote_name
          self.master_branch = master_branch
  
      def _filtered_remotes(self, origin, skip=[]):
          """
          Returns a list of remote refs, skipping ones you don't need.
  
          If ``skip`` is empty, it will default to ``['HEAD',
          self.master_branch]``.
          """
          if not skip:
              skip = ['HEAD', self.master_branch]
  
          refs = [i for i in origin.refs if not i.remote_head in skip]
  
          return refs
  
      def _master_ref(self, origin):
          """
          Finds the master ref object that matches master branch.
          """
          for ref in origin.refs:
              if ref.remote_head == self.master_branch:
                  return ref
  
          raise MissingMasterBranch(
              'Could not find ref for {0}'.format(self.master_branch))
  
      @property
      def _origin(self):
          """
          Gets the remote that references origin by name self.origin_name.
          """
          origin = None
  
          for remote in self.repo.remotes:
              if remote.name == self.remote_name:
                  origin = remote
  
          if not origin:
              raise MissingRemote('Could not find the remote named {0}'.format(
                  self.remote_name))
  
          return origin
  
new_contents: class MissingRemote(Exception):
  
      """
      Raise when a remote by name is not found.
  
      """
  
  
  class MissingMasterBranch(Exception):
  
      """
      Raise when the "master" branch cannot be located.
  
      """
  
  
  class BaseOperation(object):
  
      """
      Base class for all Git-related operations.
  
      """
      def __init__(self, repo, remote_name='origin', master_branch='master'):
          self.repo = repo
          self.remote_name = remote_name
          self.master_branch = master_branch
  
      def _filtered_remotes(self, origin, skip=[]):
          """
          Returns a list of remote refs, skipping ones you don't need.
  
          If ``skip`` is empty, it will default to ``['HEAD',
          self.master_branch]``.
          """
          if not skip:
              skip = ['HEAD', self.master_branch]
  
          refs = [i for i in origin.refs if not i.remote_head in skip]
  
          return refs
  
      def _master_ref(self, origin):
          """
          Finds the master ref object that matches master branch.
          """
          for ref in origin.refs:
              if ref.remote_head == self.master_branch:
                  return ref
  
          raise MissingMasterBranch(
              'Could not find ref for {0}'.format(self.master_branch))
  
      @property
      def _origin(self):
          """
          Gets the remote that references origin by name self.origin_name.
          """
          origin = None
  
          for remote in self.repo.remotes:
              if remote.name == self.remote_name:
                  origin = remote
  
          if not origin:
              raise MissingRemote('Could not find the remote named {0}'.format(
                  self.remote_name))
  
          return origin
  
subject: Remove useless pass