An interesting prison

While kibitzing at Street Chess yesterday I spied the following position. With White to move (as it was) the bishop is helpless against the advance of the b pawn. And so it turned out. White pushed the pawn and eventually the bishop has to sacrifice itself. Oddly enough Black waited for this by shuffling his king between f8 and g8, so when the Black captured the pawn on b7, the king was on g8, resulting in the knight returning to d6 before the King could escape via e8.
I'm not sure that this was deliberate, as when White executed the second part of the winning plan (by marching the king to e7), Black had exchanged the h pawns, and set a couple of stalemate tricks (eg King on h7 when White could promote on f8 (f8(Q) or f8(R) would stalemate). However White kept his head and wasted a move so that f8(Q) was a check, soon followed by mate.