old_contents: import sys
  
  BACKENDS = {
      'bzr': 'bzr',
      'git': 'git',
      'hg': 'hg',
      'svn': 'svn',
  }
  
  def get_backend(backend):
      if backend in BACKENDS:
          path = 'pyvcs.backends.%s' % backend
      else:
          path = backend
      __import__(path)
      return sys.modules[path]
  
new_contents: import sys
  
  AVAILABLE_BACKENDS = {
      'bzr': 'bzr',
      'git': 'git',
      'hg': 'hg',
      'svn': 'svn',
  }
  
  def get_backend(backend):
      if backend in AVAILABLE_BACKENDS:
          path = 'pyvcs.backends.%s' % backend
      else:
          path = backend
      __import__(path)
      return sys.modules[path]
  
subject: switch name to something better