Comment 2 for bug 1912688

From the functional test:

2021-01-21 21:21:05 INFO juju-log cluster:2: Configuring instance for clustering: 172.17.105.14.
2021-01-21 21:21:06 INFO juju-log cluster:2: Adding instance, 172.17.105.14, to the cluster.
2021-01-21 21:21:07 ERROR juju-log cluster:2: Failed adding instance 172.17.105.14 to cluster: Cannot set LC_ALL to locale en_US.UTF-8: No such file or directory
^[[33mWARNING: ^[[0mA GTID set check of the MySQL instance at '172.17.105.14:3306' determined that it contains transactions that do not originate from the cluster, which must be discarded before it can join the cluster.

172.17.105.14:3306 has the following errant GTIDs that do not exist in the cluster:
70fc52c0-5c2e-11eb-88ae-fa163ec8b92c:1-16

^[[33mWARNING: ^[[0mDiscarding these extra GTID events can either be done manually or by completely overwriting the state of 172.17.105.14:3306 with a physical snapshot from an existing cluster member. To use this method by default, set the 'recoveryMethod' option to 'clone'.

Having extra GTID events is not expected, and it is recommended to investigate this further and ensure that the data can be removed prior to choosing the clone recovery method.
^[[31mERROR: ^[[0mThe target instance must be either cloned or fully provisioned before it can be added to the target cluster.
Traceback (most recent call last):
  File "<string>", line 3, in <module>
SystemError: MYSQLSH (51153): Cluster.add_instance: Instance provisioning required

I confirmed this by repeating the functional test manually. So rather than the patchset change. I would rather look closer at the particular failure you saw on site.