KBFS - Input/output error after changing accounts

Earlier today I signed out of my personal keybase account and created a new one, just for this laptop (i.e. just for work, so I can separate work and personal stuff). I had to fully quit and restart the app (macOS) in order for KBFS to start working, and things have been working as expected for the past few hours, but I just tried to save a file in one of the team folders and it came back with `Input/output error`.

On the work laptop (where this issue happened), I ran `du -sh /keybase/team/*` to make it scan everything. There are two team folders exhibiting this behaviour (you should see the names in the log comments.)

On my personal laptop (also macOS, signed into my personal Keybase account, which is also an owner/admin of the same set of teams) the same `du -sh /keybase/team/*` command worked as expected, and showed disk usage numbers in the ranges I expected.

my log id: 442894da323c144d5e92641c

Start by reproducing the account switch and restart sequence on macOS, then run `du -sh /keybase/team/*` on the affected and unaffected laptops. Use log id 442894da323c144d5e92641c and the team names from the log comments to compare the failures. Done means the affected team folders can be scanned and files can be saved without an Input/output error.

Written by the indexing model from the issue text.