PROBLEM
-------

1. We are inserting a base column entry which causes an invalid value
   by the function provided to generate virtual column,but we go ahead
   and insert this due to ignore keyword.
2. We then delete this record, making this record delete marked in innodb.
   If we try to insert another record with the same pk as the deleted
   record and if the rec is not purged ,then we try to undelete mark this
   record and try to build a update vector with previous and updated value
   and while calculating the value of virtual column we get error from
   server that we cannot calculate this from base column.
   Innodb assumes that innobase_get_computed_value() Should always return
   a valid value for the base column present in the row. The failure of
   this call was not handled ,so we were crashing.

FIX
---
Handled the failure of innobase_get_computed_value()
call. We now return error in this case and prevent a
crash.