The solution was to treat differently the first move of the PV.
In analyzing this game :
[Event "z"]
[Site "?"]
[Date "2012.01.01"]
[White "x"]
[Black "y"]
[Result "1-0"]
[PlyCount "80"]
1. e4 d6 2. d4 Nf6 3. Nc3 e5 4. Nf3 Nbd7 5. Bc4 Be7 6. O-O O-O 7. a4 c6 8.
a5 exd4 9. Nxd4 Nxe4 10. Bxf7+ Rxf7 11. Ne6 Qe8 12. Nxe4 d5 13. Nc7 Qf8 14.
Ne6 Qe8 15. Nc7 Qf8 16. Nxa8 dxe4 17. Be3 Ne5 18. Qd4 Ng4 19. h3 c5 20.
Qxe4 Bf5 21. Qxb7 Nf6 22. Qxa7 Bd6 23. Qa6 Bb8 24. Rfd1 Qe8 25. Qc4 Be4 26.
Nb6 Bc7 27. Qxc5 Bxg2 28. Kxg2 Qe4+ 29. Kg1 Qe6 30. Bf4 Ne4 31. Qc4 Qg6+
32. Kf1 Qf5 33. Rd7 Qxh3+ 34. Ke1 Qh1+ 35. Qf1 Qh5 36. Rxf7 Qxf7 37. Bxc7
Qe8 38. Qc4+ Kh8 39. Be5 Nd6 40. Qc5 Ne4 1-0
After move 14..Qe8, we got this position :
[d]r1b1q1k1/pp1nbrpp/2p1N3/P2p4/4N3/8/1PP2PPP/R1BQ1RK1 w - - 4 15
Here, Nc7 is clearly winning because it's only the second repetition but SF gives 0.00
