Private key passphrase needed even with --no-import flag

I am attempting to upload a second public key to keybase, without allowing access to the associated private key. When I run `keybase pgp select --no-import --multi`, it asks for the passphrase to unlock the secret key, giving the reason as "to import into the keybase keyring." As I understand it, the --no-import flag is supposed to prevent this from happening.

Start by reproducing `keybase pgp select --no-import --multi` and trace the handling of the `--no-import` option and passphrase prompt. Done means the command does not request the private-key passphrase or import the key when `--no-import` is supplied, while preserving the intended multi-key selection behavior.

Written by the indexing model from the issue text.