The installation breaks in all sort of ways.  It first breaks by looking for mysqladmin in the ./pgsql/bin directory. After fixing that, the upgrade breaks midway with an "Unable to start MySQL server on port 3306, since another instance of mysql is running in this port."  error.   If you try stopping mysql before the upgrade, the upgrade errors out right away so that isn't an option either.

I've been able to upgrade through multiple builds in v8 and v9 up to  build 9009 without ever running into issues.  It completely breaks however in build 9200 so it looks like the upgrade process is now doing something different.

I've reached out to support and they've indicated the mysql is no longer supported as of v8.2  (build 8200) but that doesn't make any sense to me.  All the documentation (install docs, system requirements, FAQ) on the website still list MySQL as a supported DB platform.

If anyone has had any success, would love to hear it.  Migrating to MS SQL or Postgres isn't an option for us.