Why draw?

71. g7 ...
...
90. ... Kg1 Draw???
why? Rule 50 moves is not applicable

Repetition - moves 73, 81, and finally 90, all have the same position on the board after black moves.

tnx @Bibliophile0
I thought that the repetition should be a contract

See en.wikipedia.org/wiki/Threefold_repetition for more examples