Yep seen that one before XS
But have a closer look the fracture is at the top of the bracket on the pressure side
Looks more like a fracture caused where the metal was bent
I can see two reasons for this
A- the metal had an incursion or was to cold when bent
B-the bolts that hold the bracket have worked loose thus putting extra stress on the top bolt causing the fracture
I would tend to agree with you about not bocking on it just for safetys sake until it was replaced
But that would be my advice to others
If it was mine I would look at the worst that could happen if the fracture increased and I don't think it would cause a catastophic failure like in your picture so if it was my only pair I would check it before bocking during and after until I got the new bit
So flamingsword26 as usual your choice at your own risk
but if we wanted to be safe we would have taken up knitting
Jason