fix presence of is_min_version during read_metadata

            desc.update(json.loads(img_desc))

            self.check_image_name(desc["name"])

            self.check_image_version(desc["version"])

            # add is_min_version if not present

            if "is_min_version" not in desc:

                desc["is_min_version"] = 0

            # check installsystems min version

            if "is_min_version" in desc:

            if self.compare_versions(installsystems.version, desc["is_min_version"]) < 0:

                raise Exception("Minimum Installsystems version not satisfied")

        except Exception as e: