exports_deply_funcs() used to log the core version as nil. The problem
is the fact, that table.concat was used for core version string, so the
complied exports always had nil instead of core_version.
table.concat doesn't work with non-array tables, as they have no defined
order. Let's explicitly define __tostring function for version and use
it in order to log core version.
storage: fix schema log message
exports_deply_funcs() used to log the core version as nil. The problem is the fact, that table.concat was used for core version string, so the complied exports always had nil instead of core_version.
table.concat doesn't work with non-array tables, as they have no defined order. Let's explicitly define __tostring function for version and use it in order to log core version.
Closes https://github.com/tarantool/vshard/issues/465
NO_DOC=bugfix