The reasons for failures to initialize a user collation defined
in Index.xml are now correctly reported                                  
(in SHOW WARNINGS and in the server error log) if the COLLATE clause
is used with an expression, e.g.:

  SELECT <exrp> COLLATE <collation name> FROM t1;

Previously, the failure reasons were reported only by COLLATE clauses
in SET NAMES and in DDL statements, e.g.:

  SET NAMES utf8 COLLATE utf8_xxx_ci;
  CREATE TABLE t1 (a VARCHAR(1) CHARACTER SET utf8 COLLATE utf8_xxx_ci);