The limit down to 127 is needed cause of a long time bug in mysql. The
error message looks like this when creating an index.
Mysql2::Error: Specified key was too long; max key length is 1000 bytes
So with utf8 (3 bytes for one char) you exceed this with two
varchar(255).
See http://bugs.mysql.com/bug.php?id=4541 guru meditation
Signed-off-by: Andreas Schneider <asn@cryptomilk.org>