If you haven’t noticed, your Azure Website’s SCM site has been updated to work with Azure Single Sign-on. Earlier, it was prompting for a basic authentication prompt where you enter your publishing credentials, but now, you can just login using your Microsoft Account which you are using for your Azure Subscription.
For example, if I go to my site https://<mysite>.scm.azurewebsites.net, it shows me the below:
If I’m already logged into my Microsoft Account, say, I’m already on the Azure Management Portal, I don’t even see this if I’m going to the SCM site. It takes directly into the SCM site. However, in case if you need the basic authentication, you can append /basicauth in the url, like https://<yourwebsite>.scm.azurewebsites.net/basicauth to get the basic authentication prompt.