Report back the list of issues with an installed package (like rpm -V pkgname):

yb = yum.YumBase()
pkgs = yb.rpmdb.searchNevra(name='yum')
for pkg in pkgs:
    errors = pkg.verify()
    for fn in errors.keys():
        for prob in errors[fn]:
            print '%s - %s' % (fn, prob.message)