inconsistent presence of move indication numbers (black moves)

[niklasf]

in games without engine evaluations only.

is:

1. e4 { [%clk 0:02:00] } e5 { [%clk 0:02:00] }

should be:

1. e4 { [%clk 0:02:00] } 1... e5 { [%clk 0:02:00] }

---

originally reported in lichess-org/lila#7811

[niklasf]

+8% uncompressed:

$ du *2017-04.pgn
23591956	lichess_db_standard_rated_2017-04.pgn
25522724	rewritten_2017-04.pgn

[niklasf]

+9% compressed:

$ du *
2877532 lichess_db_standard_rated_2017-04.pgn.bz2
3134380 rewritten_2017-04.pgn.bz2

[ornicar]

we could regen the whole thing some day.