The counter metadata_table_reference_count was not updated consistently
ever since mysql-server@65c0af9a1dedae43b63797134aff6b32304ced52
or commit 2e814d47
introduced dict_table_t::release().

The counter metadata_table_handles_closed was being incremented
unconditionally in ha_innobase::close(), while the corresponding
counter metadata_table_handles_opened would be incremented in
ha_innobase::open() if the function returned early due to an error.