To reproduce:
You can never get past the Create Account screen, because the Login activity always launches the Create Account activity unconditionally.
When fixing this issue, see if it's possible to fix it by removing code, instead of adding it.
Reminder for QA:
To enable "Don't keep activities", go to the Developer settings of the device itself (not the app), and scroll nearly all the way down. There should be a switch that says "Don't keep activities". Enable it, then perform the test. Afterwards make sure to set it back to disabled, since it will impact/degrade performance of the device.
I was able to log in and out with 'don't keep activities' enabled on 2.7.50333-alpha-2020-10-29