Sometimes a parameter slot may not get a value because of the protocol
 data being plain wrong.
 Such cases should be detected and handled by returning an error.
 Fixed by checking data stream constraints where possible (like maximum
 length) and reacting to the case where a value cannot be constructed.


sql/sql_prepare.cc:
  Bug #28934: 
   - check for a parameter slot not being set because 
      of wrong data
   - check if the length read from the stream is not
      greater than the maximum length of the field
tests/mysql_client_test.c:
  Bug #28934: test case