By adding pos.non_pawn_material(pos.side_to_move()) as a precondition in step 13,
which is already in use in Futility Pruning (child node) and Null Move Pruning for similar reasons.
Pawn endgames, especially those with only 1 or 2 pawns, are simply heavily influenced by zugzwang situations.
Since we are using a bitbase for KPK endgames, I see no reason to accept buggy evals as shown in #760
Patch looks neutral at STC
LLR: 2.32 (-2.94,2.94) [-3.00,1.00]
Total: 79580 W: 10789 L: 10780 D: 58011
and LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27071 W: 3502 L: 3390 D: 20179
Bench: 6259071
Closes#1051Closes#760
72a501c6fe