Here's what the transaction history looked like on the corresponding diff:

I just observed an isolated occurrence of this. On the same setup, and on the same day, it's worked correctly every time except once.

Hmm, so are "Subtasks" and "Blocking Tasks" distinct features? You're right in that the exact text of what I'm seeing is "$user added a blocking task: $t", but is "Create Subtask" not the same as "Create Task" + "Edit Blocking Tasks" for the parent?

Those are a bit older; don't remember. Probably I created the tasks first and then linked them explicitly via Edit Blocking Tasks, Manage Dependencies, or whatever it was called at the time.

Yep, I'm a bit behind rPd1c3915e3aa5. Thanks.

/tmp being full probably doesn't apply to me, since i don't have a special mount-point for it, so it should be sharing in the bounty of ~28GB of free space on /dev/sda1. Someone did pull the plug on the machine, but that was probably about half a year ago, and I haven't noticed these errors until just now.

Ah, thanks. Is there any way to re-run the original operation that failed here from the cli?

Seeing the same thing on this instance:

Ah, never mind, I understand now. It's exactly the thing I was doing.

What's the syntax for a multi-paragraph list item?

Related issue: T4979