This method was a shallow wrapper around registryclient.NewRegistryClient but
due to its signature resulted in various dependencies becoming a dependency
of the "command" package. Consequence of this was that cli-plugins, which
need the cli/command package, would also get those dependencies. It is no
longer used, and was deprecated in 8ad07217dc.
This patch removes the RegistryClient method from the interface
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
5ea072d936