This is the version we have in global-requirements, and it does not
contain module pint.errors. Fortunately, in all versions the required
error is exposed on the top level, so just use it.
See https://review.rdoproject.org/r/6741 for a build failure.
Change-Id: I1f194ccc48a3195fcbf8599c3a0b4fa21fde16d2