Improve deduping of commits (reverts) and for pre-releases

[devversion]

We should dedupe reverts (Andrew K mentioned this in the past -- not sure if we have an issue for it)

Also we should look into improving the deduping for next/FF/RC pre-releases. Commits that also went into patch should not show up again. We have good deduping for other scenarios but our release notes compare range deduping is not ideal for pre-releases because we only compare to the previous pre-release, but should also dedupe anything that is part of the patch branch already.