@staticmethod
    def by_env():
        for (execname, cvstype, msg) in [('git', CVSType.GIT, 'GitExecutableFound'),
                                         ('bzr', CVSType.BZR, 'BazaarExecutableFound')]:
            if check_installed_rcs(execname):
                return (cvstype, msg)

        return (None, None)
Provides the cvs (repo) type by checking environment variable
dataset/ETHPy150Open cloudControl/cctrl/cctrl/app.py/CVSType.by_env