ERROR: duplicate key violates unique constraint "pg_class_relname_nsp_index"

When running Embulk on multiple machines that writes to a single RedShift cluster, I often get the following error **(usually only on the first few runs)**:

`Error: java.lang.RuntimeException: org.postgresql.util.PSQLException: ERROR: duplicate key violates unique constraint "pg_class_relname_nsp_index" (possibly caused by concurrent transaction conflict)`

I found these two issues that seems related but both seems to be fixed in versions older than the one I'm using:
https://github.com/embulk/embulk-output-jdbc/issues/205 https://github.com/embulk/embulk-output-jdbc/issues/116

Embulk and plugin versions:
> Embulk v0.9.11
> embulk-input-mysql (0.9.3)
> embulk-output-redshift (0.8.1)

No source file or test is named. Start by reviewing related issues #205 and #116 and reproducing the failure with Embulk 0.9.11, embulk-input-mysql 0.9.3, and embulk-output-redshift 0.8.1 against one Redshift cluster from multiple machines; done means the concurrent first-run failure has a verified resolution.

Written by the indexing model from the issue text.