Transactional locks hanging for non-transactional migrations

Which version and edition of Flyway are you using?

• org.flywaydb:flyway-core:9.1.2

If this is not the latest version, can you reproduce the issue with the latest one as well? (Many bugs are fixed in newer releases and upgrading will often resolve the issue)

• It is the latest version

Which client are you using? (Command-line, Java API, Maven plugin, Gradle plugin)

• Java API

Which database are you using? (Type & version)

• Postgres 12.4

Which operating system are you using?

• Docker container with Linux running on macOS

What did you do? (Please include the content causing the issue, any relevant configuration settings, the SQL statement(s) that failed (if any), and the command you ran)

• Upgrading to flyway 9.1.2 caused existing migrations to hang indefinitely
• We have non-transactional migrations (e.g. CREATE INDEX CONCURRENTLY index_name ON table_name(column_name) that no longer work because the default behavior of flyway with postgres is to use a transactional lock starting flyway 9.1.2 (see https://github.com/flyway/flyway/commit/022a646b7959aa7a9a11760d8e93e5e238fbd6ec)
• Disabling the transactional log (flyway.postgresql.transactional.lock=false) works fine, but is such breaking behavior expected from a patch release?
• Does this interaction between non-transactional migrations and transactional locks make sense?

What did you expect to see?

• Existing migrations to keep working after upgrading to 9.12

What did you see instead?

• Existing (non-transactional) migrations hang indefinitely