Compatibility between credsStore and passphrase.

[yueli9]

My situation is we have two different registries. One uses the traditional passphrase, the other uses the credsStore which is Amazon ecr-login.
It seems that the docker-client would try to use credsStore to login to both of the registries, which will lead to an error.
Currently, I get around with this by creating a separate config.json file for ecr. But this lead to a lot of hassles.

Could you consider to change the configuration of docker-client? For example, it will use the passphrase if the passphrase part if not NULL. Otherwise, it will try to use the credsStore.