The `unittest2` package is simply a backport of `unittest` from the
Standard Library of Python 2.7 to previous versions.
There is no reason to use it any longer.
Closes#6941
- pass around the assertion_report to the YAML importer
- removed TestReport, which was identical to assertion_report
- assertion_report is simpler (no more severity level)
- use the report to log a greppable sentence when some test failed.
Previously the runbot had to grep for a Traceback which was an
unreliable technique (e.g. an exception can be purposefuly
generated as part of a test and the associated traceback
visible in the logs). Now it can grep
"At least one test failed when loading the modules".
bzr revid: vmt@openerp.com-20120302110227-nqrl7i46ju28ntdr