innodb_zip.recover failed in buildbot

innodb_zip.recover 'innodb'              w4 [ fail ]  Found warnings/errors in server log file!

        Test ended at 2017-05-11 18:35:21

line

2017-05-11 18:35:19 3057604352 [ERROR] mysqld: Table './mysql/plugin' is marked as crashed and should be repaired

2017-05-11 18:35:19 3057604352 [ERROR] mysqld: Table 'plugin' is marked as crashed and should be repaired

2017-05-11 18:35:19 3057604352 [Warning] Checking table:   './mysql/plugin'

2017-05-11 18:35:19 3057604352 [ERROR] mysql.plugin: 1 client is using or hasn't closed the table properly