'Make sure that the file is writeable.
Useful if our source is read-only.'

def make_writeable(self, filename):

    if sys.platform.startswith('java'):
        return
    if (not os.access(filename, os.W_OK)):
        st = os.stat(filename)
        new_permissions = (stat.S_IMODE(st.st_mode) | stat.S_IWUSR)
        os.chmod(filename, new_permissions)
