ignore command exit codes

Issue #124 on hold
Tarek Ziadé
created an issue

Sometimes it's desirable to ignore the exit code of a command, in the commands option of a testenv section.

I would like to suggest adding a "-" prefix like in Makefiles. When a command has such a prefix, tox should ignore the exit code of that command.


commands = coverage erase
           {envbindir}/python setup.py develop
           coverage run -p setup.py test
           coverage combine
           - coverage html
           {envbindir}/flake8 loads

Here, the 5th command may return false, but this can be ignore