Click 8.0.0 `group.add_command(..)` does not replace name in description and when looking up defaults

[boidolr]

With click 8.0.0 click.group.add_command(..) changed the behavior in how new command names are used:
Both the help text for the command as well as when looking up default values in default_map the previous command name instead of the one added by the group are shown.

Minimal example:

# test.py
import click

@click.command()
@click.option(
    "--qux",
    required=True
)
def foo(qux):
    print(qux)

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

group.add_command(foo, "bar")

group(default_map={"bar": {"qux": "val"}})

Run the above:

• with click 7.x:

$ python3 test.py bar --help
Usage: test.py bar [OPTIONS]
// and
$ python3 test.py bar
val

• with click 8.0.0:

$ python3 test.py bar --help
Usage: test.py foo [OPTIONS]
// and
$ python3 test.py bar
Usage: test.py foo [OPTIONS]
Try 'test.py foo --help' for help.

Error: Missing option '--qux'.

I would have expected that both the help shows the name of the command as "bar" (as using "foo" will result in an error)
and the lookup for the default using "bar" as a key.

Environment:

• Python version: 3.9.5
• Click version: 8.0.0

[davidism]

This was due to #1422, which was intended to return the "real" command name when using aliases. However, I think the use case you've shown here is much more common, so I'll revert that change. The aliased command issue can be addressed by updating the docs to override resolve_command and return the desired command name instead.