cli test failures when ~/.ubuntu-ci does not exist (isolation issue)

While setting my laptop with trunk @ revno 302, I encounter the following failures:

======================================================================
ERROR: test_cli_changes_file_is_something_else (tests.test_cli.MainScriptTestCase)
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Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/mock.py", line 1201, in patched
    return func(*args, **keywargs)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/test_cli.py", line 274, in test_cli_changes_file_is_something_else
    self.cli.main(args, log=logger)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/../ubuntu-ci", line 113, in main
    utils.load_config(DEF_CFG)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/ci_libs/utils.py", line 56, in load_config
    sys.exit(error_msg.format(config_file, "\n ".join(r), sys.argv[0]))
SystemExit: ERROR: Missing YAML config in /home/vila/.ubuntu-ci:
 ci_url
 auth_url
 auth_user
 auth_password
 auth_region
 auth_tenant_name

This can be created by running: ./cli/setup.py auto_config

======================================================================
ERROR: test_cli_changes_file_is_unreleased (tests.test_cli.MainScriptTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/mock.py", line 1201, in patched
    return func(*args, **keywargs)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/test_cli.py", line 292, in test_cli_changes_file_is_unreleased
    self.cli.main(args, log=logger)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/../ubuntu-ci", line 113, in main
    utils.load_config(DEF_CFG)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/ci_libs/utils.py", line 56, in load_config
    sys.exit(error_msg.format(config_file, "\n ".join(r), sys.argv[0]))
SystemExit: ERROR: Missing YAML config in /home/vila/.ubuntu-ci:
 ci_url
 auth_url
 auth_user
 auth_password
 auth_region
 auth_tenant_name

This can be created by running: ./cli/setup.py auto_config

======================================================================
ERROR: test_cli_dsc_file_in_disguise (tests.test_cli.MainScriptTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/mock.py", line 1201, in patched
    return func(*args, **keywargs)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/test_cli.py", line 256, in test_cli_dsc_file_in_disguise
    self.cli.main(args, log=logger)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/tests/../ubuntu-ci", line 113, in main
    utils.load_config(DEF_CFG)
  File "/home/vila/ci/ubuntu-ci-services-itself/trunk/cli/ci_libs/utils.py", line 56, in load_config
    sys.exit(error_msg.format(config_file, "\n ".join(r), sys.argv[0]))
SystemExit: ERROR: Missing YAML config in /home/vila/.ubuntu-ci:
 ci_url
 auth_url
 auth_user
 auth_password
 auth_region
 auth_tenant_name

This can be created by running: ./cli/setup.py auto_config

----------------------------------------------------------------------
Ran 48 tests in 0.237s

FAILED (errors=3)

The tests should not rely on the existence (or content) of a file under user control but create one suiting their need.

This an edge case we can fix later.