Comment 4 for bug 1389743

Markus,

Thanks for the additional detail. Verified as described. The differences of converting numeric type to binary string prior to 5.5.3 vs non-binary string as of 5.5.3 and after indeed causes different results when concat with multi-bytes string values.

my.cnf
-------------
character-set-server=utf8
skip-character-set-client-handshake

In 5.1, concat(id, name) caused the name column to be converted to binary string:

> select concat(id, name) from t1;
+------------------------------------------+
| concat(id, name) |
+------------------------------------------+
| 14LATIN SMALL LETTER U WITH DIAERESIS ü |
+------------------------------------------+

In 5.5, concat(id, name) makes no cast on name column:
> select concat(id, name) from t1;
+--------------------------------------------+
| concat(id, name) |
+--------------------------------------------+
| 14LATIN SMALL LETTER U WITH DIAERESIS ü |
+--------------------------------------------+