The UNIV_DEBUG version asserted if a foreign key check failed because of a lock wait timeout
btr0cur.c:
  Fix a bug: if the primary key was updated (or delete + insert) so that only the case of characters changed, we were left with a dangling adaptive hash index pointer, often causing an assertion failure in page0page.ic line 515


innobase/btr/btr0cur.c:
  Fix a bug: if the primary key was updated (or delete + insert) so that only the case of characters changed, we were left with a dangling adaptive hash index pointer, often causing an assertion failure in page0page.ic line 515
innobase/row/row0ins.c:
  The UNIV_DEBUG version asserted if a foreign key check failed because of a lock wait timeout