Premature gameover on line clear about tetris

[0xjmux]

Not resolved - similar crash occurred on a 4 row clear in a game a couple minutes ago - see test/files/final-gamestate-4row-clear-premat-gameover.ini

It looks like some weirdness is causing incorrect bit values to show up at the top of the file, which prevents the new piece from moving down - triggering the game over condition. Need to figure out what is causing the corruption in the first place.

[0xjmux]

• possible cause might be clearing lines down to row 31
• it seems to happen right around when the level increases, so maybe it's the change in level that's doing it?

[0xjmux]

Issue possibly fixed in 6a23430, but until i've gone through several rounds of testing trying to break it will leave this open.

[0xjmux]

Commit 6a2340 fixed this issue.
As I stated in the commit, the problem and fix were:

* clear_rows modified so it won't try to move rows above the top of the
  board down, which is a possible cause of the premature crash as a
  result of garbage data I've been seeing (Issue https://github.com/0xjmux/tetris/pull/2). Garbage data ends up in the
  first few rows, pieces can't move down into it, they stop falling, and
  then the game_over condition activates.
    * to fix this, added another loop to clear_rows() so that it stops
      once it would start touching the top of the board, and will fill
      rows at the top with BG_COLOR without trying to read OOB