You post it on a user forum. You ask around on IRC, and you find somebody who can reproduce your problem on a different system architecture. (Ha, I’m not crazy!)
You investigate a bit, but nothing obvious shows up.
Monday morning, you post to IRC once more, and some other people have useful things to say. (“Downgrade this, and it will work.” — “I think there was an upstream fix”).
And a few minutes later: “patched version will be in the repositories in about 10-15 minutes”.
Try that from a commercial vendor, even with the most premium support their offer.
Thanks the awesome Arch Linux ARM community, and IRC users leming, fogobogo, Xogium, and redfish.