Running a test with pdb was difficult because testr captures
output and causes pdb prompt to quit.
Tips for how to run with debug are provided here:
https://wiki.openstack.org/wiki/Testr#Debugging_.28pdb.29_Tests
This change puts these commands into a debug env in tox.ini so
you can do a command like
tox -e debug test_v3_trust_token_get_token_fails
or, for more granularity:
tox -e debug keystone.tests.test_sql_migrate_extensions.EndpointFilterExtension
tox -e debug keystone.tests.test_sql_migrate_extensions.EndpointFilterExtension.test_downgrade
and when it hits your breakpoint you'll get the debug prompt.
Change-Id: I2b5dc81f4652dc89ecbcc7c785245a81cf77a1ca
c8302509e6