There are several differences between this and testr which we
need to discuss. Let's wait until after the v3 release so we
don't delay it further.
This reverts commit 68e02466ce.
stestr is actively maintained. OpenStack is migrating to stestr,
go ahead and follow suit.
As part of this, shift the default values for STDOUT capture into the
tox.ini file. This preserves the current behavior of tox doing
capture and running tests directly not capturing.
Remove the depend on python-subunit... stestr takes care of that for us.