Here's a view of the treble side of a more-or-less typical early-20th-century factory fiddle.
When looking at a used/vintage fiddle with the idea of purchase, this is a good area to examine closely.
Note the little bent "line" near the far-right peg hole. Look closer.
This is a crack, and it's a crack that would put me off purchasing the instrument unless there were some other highly attractive parts that would make the cost of repair worth it. This type of crack needs serious repair, not just a simple glueing.
It's probably the most common location for a peg-box crack, on the A-peg of a violin (or the D-peg of a viola or cello), because often the grain runs out towards the carved edge. This one is a bit unusual, in that the grain is twisty here and the crack follows that twisty grain. Often, it is a straight crack, following the straight-grain of the pegbox.
I'll have to talk to the customer to see what they want to do with this. It can be repaired. Simply a matter of worth and value, which needs some thought.