[BUG] Logged out after update to 5.3.0 - device name in use

After updating my iOS device to 5.3.0 I was logged out of the app. When I logged in again I was prompted to give this device a name, of course I gave it the same name as I used previously because it is the same device, but now the Keybase app complains that

> You've already used this device name. For security reasons, pick another name.

I should not need to pick another name for my existing device just because I was logged out.

No files, tests, or entry points are identified. Start by tracing the iOS login and device-name flow around the 5.3.0 update, then verify how an existing device name is handled after logout; done means reproducing the regression and confirming the prior name is accepted again.

Written by the indexing model from the issue text.