There are a few cases where we are passing non-string arguments to

methods that make API calls, which was fine in the past. However, we are

now assuming that all arguments are strings and erroring out if they are

not.
Instead, we now make a best-case attempt to serialize values to strings

and produces a better error message when this process fails.

Confirmed the following hold true on Python versions 2.7, 3.5, 3.6, and

3.7:

With this patch applied, rbt status prints the list of status, where

  previously it would throw an exception due to attempting to stringify

  non-string values.
With this entire patch stack (/r/10695, /r/10696, and /r/10697),

rbt post is able to create review requests with commit history.