innodb_fts.innodb_fts_plugin failed in buildbot with errors in server log

innodb_fts.innodb_fts_plugin 'innodb'    w2 [ fail ]  Found warnings/errors in server log file!

        Test ended at 2017-09-06 15:02:02

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2017-09-06 15:01:58 139764074350784 [ERROR] mysqld: Table './mysql/plugin' is marked as crashed and should be repaired

2017-09-06 15:01:58 139764074350784 [ERROR] mysqld: Table 'plugin' is marked as crashed and should be repaired

2017-09-06 15:01:58 139764074350784 [Warning] Checking table:   './mysql/plugin'

2017-09-06 15:01:58 139764074350784 [ERROR] mysql.plugin: 1 client is using or hasn't closed the table properly

^ Found warnings in /dev/shm/var/2/log/mysqld.1.err