Mi_bt sensor error upgrading to 0.99

I was about to upgrade to latest (raspberry pi 3, rasbian strech+docker+hass.io) from 0.98 and used the “Check Home Assistant configuration” add-on and it resulted in the following error:

failed config
  General Errors: 
    - Platform error sensor.mitemp_bt - No module named 'pexpect'

Successful config (partial)

Any ideas how to resolve this issue?