Must have been a poor braze joint to start with as you did not really had to go that much with the cold set.
Maybe consider yourself lucky, it broke off in your shop, and not on the road where the brake caliper might have fallen into you rear wheel spokes, during a hard braking event.....
__________________
72 Line Seeker
83 Davidson Signature
84 Peugeot PSV
84 Peugeot PY10FC
84 Gitane Tour de France.
85 Vitus Plus Carbone 7
86 ALAN Record Carbonio
86 Medici Aerodynamic (Project)
88 Pinarello Montello
89 Bottecchia Professional Chorus SL
95 Trek 5500 OCLV (Project)