This appears to be sorta the reverse of this older bug: if I click the "Google" button by mistake and then go back to fill in my credentials, the page assumes I'm trying to log in with Google even when I click "Log in".
Steps to reproduce:
- Make sure you're logged out of Stack Exchange and Google.
- Visit the login page.
- Click "Google"
- Note that you're viewing the Google login page:
- Use your browser's "back" button to return to the login page
- Fill in an email and password
- Click "Log in" or press Enter
- Note that you're again viewing the Google login page, instead of being logged in with the credentials entered in Step 5:
- Hit back again to return to the login page.
- Refresh the page.
- Enter your email and password, and click "Log in"
- Note that you're now logged in successfully.
the Facebook button causes the same effect as the same as the Google button in this scenario
Clicking the wrong button and then returning to the previous page should not set some secret state that prevents the rest of the controls from working.
Tested in Firefox 44.0.2 and Chrome 49.0.2623.54 beta-m, both on Windows 8.1.