juju charm-resources is not working for charmhub charms

[Jorge Merlino]

When juju charm-resources is run on a charmhub charm it returns an error:

$ juju charm-resources etcd --channel latest/stable --debug
...
ERROR charm repository for source "ch" not supported (not supported)
10:23:32 DEBUG cmd supercommand.go:537 error stack:
charm repository for source "ch" not supported (not supported)
/build/snapcraft-juju-35d6cf/parts/juju/src/rpc/client.go:178:
/build/snapcraft-juju-35d6cf/parts/juju/src/api/apiclient.go:1252:
/build/snapcraft-juju-35d6cf/parts/juju/src/api/client/charms/client.go:221:
/build/snapcraft-juju-35d6cf/parts/juju/src/cmd/juju/resource/charmresources.go:291:
/build/snapcraft-juju-35d6cf/parts/juju/src/cmd/juju/resource/charmresources.go:194:

But it works for charmstore charms:

$ juju charm-resources cs:~containers/etcd --channel stable
Resource Revision
core 0
etcd 3
snapshot 0

Tested in juju 2.9.26-ubuntu-amd64

[Heather Lanigan (hmlanigan)]

https://github.com/juju/juju/pull/13852