EGN on promotion is incorrect

[andersfylling]

Generating EGN for a game state where a promotion takes place results in incorrect behavior:
"rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8"

  +---+---+---+---+---+---+---+---+
8 | r | n | b | q | - | k | - | r | 
  +---+---+---+---+---+---+---+---+
7 | p | p | - | P | b | p | p | p | 
  +---+---+---+---+---+---+---+---+
6 | - | - | p | - | - | - | - | - | 
  +---+---+---+---+---+---+---+---+
5 | - | - | - | - | - | - | - | - | 
  +---+---+---+---+---+---+---+---+
4 | - | - | B | - | - | - | - | - | 
  +---+---+---+---+---+---+---+---+
3 | - | - | - | - | - | - | - | - | 
  +---+---+---+---+---+---+---+---+
2 | P | P | P | - | N | n | P | P | 
  +---+---+---+---+---+---+---+---+
1 | R | N | B | Q | K | - | - | R | 
  +---+---+---+---+---+---+---+---+
    A   B   C   D   E   F   G   H 

the promotion at D7 gets the EGN H1C8.