for a seemingly impoosbile conds in WHERE....

This crashed MySQL in 4.0.2


Docs/manual.texi:
  A fix for a bug which hits the optimiser when trying to group keys
  for a seemingly impoosbile conds in WHERE....
mysql-test/r/select.result:
  A fix for a bug which hits the optimiser when trying to group keys
  for a seemingly impoosbile conds in WHERE....
mysql-test/t/select.test:
  A fix for a bug which hits the optimiser when trying to group keys
  for a seemingly impoosbile conds in WHERE....
sql/opt_range.cc:
  A fix for a bug which hits the optimiser when trying to group keys
  for a seemingly impoosbile conds in WHERE....