def sanity_check(vcs):
if not vcs.is_clean_checkout():<EOL><INDENT>q = ("<STR_LIT>"<EOL>"<STR_LIT>"<EOL>"<STR_LIT>")<EOL>if not ask(q, default=False):<EOL><INDENT>sys.exit(<NUM_LIT:1>)<EOL><DEDENT><DEDENT>
Do sanity check before making changes

    Check that we are not on a tag and/or do not have local changes.

    Returns True when all is fine.