Comment 4 for bug 628419

Most likely cause is session->is_error() has not been cleared from the previous query. Then an un-used join condition is cleared in mysql_select causing segfault.

If I'm right we need to find what is dbd-drizzle does differently so that errors are not cleared and make sure the 'quick' pointer is handled nicely, I see another (unlikely) case where a segfault with this variable can happen too..