Make a command available for two groups in python click?

I'm using click to write a cli program in Python, and I need to write something like this:

import click


@click.group()
def root():
    """root"""
    pass


@root.group()
def cli():
    """test"""
    pass


@root.group()
def cli2():
    """test"""
    pass


@cli.command('test1')
@cli2.command('test1')
def test1():
    """test2"""
    print 1234
    return


root()

but this will fail with:

TypeError: Attempted to convert a callback into a command twice.

How can I share the command between multiple groups?