bzr commit into mysql-6.0 branch (kgeorge:2692) Bug#39186

[Georgi Kodinov]

#At file:///home/kgeorge/mysql/bzr/B38701-6.0-5.1.29-rc/

 2692 Georgi Kodinov	2008-09-08
      Bug #39186: Crash in String::append when inserting duplicate empty strings an uft8 SET col
      
      Fixed a problem in constructing a string representation of a ENUM field when reporting
      key duplicate error.
      Note : no test case as the one for bug #38701 covers this one as well.
modified:
  sql/key.cc

per-file messages:
  sql/key.cc
    Bug #39186: added a length check.
=== modified file 'sql/key.cc'
--- a/sql/key.cc	2008-03-27 19:02:15 +0000
+++ b/sql/key.cc	2008-09-08 14:54:16 +0000
@@ -368,7 +368,7 @@ void key_unpack(String *to,TABLE *table,
     {
       CHARSET_INFO *cs= field->charset();
       field->val_str(&tmp);
-      if (cs->mbmaxlen > 1 &&
+      if (cs->mbmaxlen > 1 && tmp.length() > 0 &&
           table->field[key_part->fieldnr - 1]->field_length !=
           key_part->length)
       {