adb does not start after reboot

On r228-r230 (earlier versions may also be affected), adb does not start on reboot.

Steps to reproduce:
1. create an image and set a PIN (there are multiple bugs in this process, so I won't enumerate all the steps to do this)
2. enable developer mode in system settings
3. phablet-shell into the image (it works)
4. reboot

At this point, after a successful reboot/power cycle, I would expect adb to start. However, 'adb devices' only shows 'offline' and phablet-shell does not work. This is a pretty serious regression in the emulator because there appears to be no workaround: unchecking and checking developer mode in system settings does not work, there is no route to the emulator ip so 'android-gadget-service enable ssh' doesn't help, and there is no terminal available for the emulator, so the only recourse is to regenerate the image (which even if you have a cached image and use --revision=... it takes a while to first boot the emulator).