Comment 6 for bug 934597

The problem does not show up when the error occurs inside
select_insert::send_data().

It only shows up when
- The "subquery returns > 1 row" error occurs when checking
  exec_const_cond (that is, at execution phase we find out that
  there won't be any matching rows).
- After that, select_insert::send_eof() fails to deal with error state.

Attempts to repeat this situation with a failure in other clause than
exec_const_cond were not successfull: I can either
- get an error in select_insert::send_data(), which is handled
- get an error elsewhere, which causes a general error condition and a
  call to select_create::abort() (and not ::send_data).