cannot log into ocp cluster with oc 4.7 client without the username (oc login vs oc login --username)

[andreaskaris]

oc login states You must obtain an API token since Red Hat OpenShift Container Platform 4.7

4.6 client:

[quicklab@upi-0 ~]$ oc login --server=https://(...):6443 --insecure-skip-tls-verify=true
Authentication required for https://api.(...):6443 (openshift)
Username: ^C

4.7 client:

[quicklab@upi-0 ~]$ oc login --server=https://(...):6443 --insecure-skip-tls-verify=true
You must obtain an API token by visiting https://oauth-openshift.apps.(...)/oauth/token/request

Did we make this change on purpose? It looks like it from #553
If so, this is really confusing to our customer base. Also, our documentation is out of date atm:
https://docs.openshift.com/container-platform/4.7/cli_reference/openshift_cli/getting-started-cli.html#cli-installing-cli_cli-developer-commands

If we really must change the oc CLI behavior (and likely there is a good reason for this change) and if we cannot default back to the old, well-known behavior, we should at least provide a Note/Warning to users for the next few versions such as:

[root@openshift-jumpserver-0 ~]# oc login
You must obtain an API token by visiting https://oauth-openshift.apps.ipi-cluster.example.com/oauth/token/request
INFO: The behavior of `oc login` changed.
INFO: If you wish to login via username and password prompt, provide the --username <username> parameter

So that we spare our customers the step to open our documentation? We also have to update our documentation.