Digging through the Augean stables of my inbox, I found this pic from gunsmith Shannon with the note "We hadn't seen this one before."
That's a new one on me, too, and I've seen a fair number of broken Glocks myself. Looking at that frontstrap, that gun could be pushing thirty, and judging by the finish wear and the way the plastic's worn shiny on the high spots, it's got some miles on it, too. I wonder what the backstory is?
See? This is why it never pays to be jaded. Thinking you've seen every way a gun can break is just plain hubris.