When restoring lastinx last_key.keyinfo must be updated as well. The
good example is in _ma_check_index().

The point of failure is extra(HA_EXTRA_NO_KEYREAD) in
ha_maria::get_auto_increment():

  1. extra(HA_EXTRA_KEYREAD) saves lastinx;
  2. maria_rkey() changes index, so the lastinx and last_key.keyinfo;
  3. extra(HA_EXTRA_NO_KEYREAD) restores lastinx but not
     last_key.keyinfo.

So we have discrepancy between lastinx and last_key.keyinfo after 3.