In r550494 meld was updated to version 3.21.0. Unluckily that version requires pygobject 3.30 or higher and fails to run with an error stating that: "Meld requires pygobject 3.30 or higher."
I've created a atch reverting the update for this port and bumping PORTEPOCH. I'm not directly committing this as "fixit blanket" because, before bumping portepoch, I'd rather get some feedback, maybe a better fix is on the way.
Otherwise I'd like to commit this ASAP.