Let's be precise before I get slammed down again by Don for saying crap 😉.
The acs-content-repository/sql/postgresql/upgrade/upgrade-5.2.0d16-5.2.0d17.sql does not work if you have upgraded acs-kernel before (I think), to 5.6.0. If I remember correctly you would have to upgrade to 5.2 first and then continue onwards to 5.6. Therefore in my opinion it might make sense to remove the acs-content-repository/sql/postgresql/upgrade/upgrade-5.2.0d16-5.2.0d17.sql from the oacs-5-6 branch, as it will break upgrades from versions before 5.2.
This being said, we run our ]po[ installations purely by checking out the latest OpenACS release branch and the ]po[ HEAD version (as this was the only one so far being able to work with OpenACS > 5.1) and have had not many issues so far (although we use an old ]po[ dumpfile as a starting point and upgrade, instead of making a new install).
