Server crashes in my_strcasecmp_utf8 on ADD KEY IF NOT EXISTS with implicit name when the key exists

create table if not exists t1 (i int);

alter table t1 add key (i);

alter table t1 add key if not exists (i);

#3  <signal handler called>

#4  0x0000000000dcc0f2 in my_strcasecmp_utf8 (cs=0x1626c40, s=0x0, t=0x7f3c6c118d39 "i") at /home/elenst/bzr/10.0/strings/ctype-utf8.c:2768

#5  0x00000000006cde3c in handle_if_exists_options (thd=0x2eea0c8, table=0x7f3c6c01e898, alter_info=0x7f3c78a4d610) at /home/elenst/bzr/10.0/sql/sql_table.cc:5147

#6  0x00000000006d21cd in mysql_alter_table (thd=0x2eea0c8, new_db=0x7f3c6c017420 "test", new_name=0x7f3c6c0498e0 "t1", create_info=0x7f3c78a4d500, table_list=0x7f3c6c046b40, alter_info=0x7f3c78a4d610, order_num=0, order=0x0, ignore=false, require_online=false) at /home/elenst/bzr/10.0/sql/sql_table.cc:6663

#7  0x000000000097e246 in Alter_table_statement::execute (this=0x7f3c6c017560, thd=0x2eea0c8) at /home/elenst/bzr/10.0/sql/sql_alter.cc:106

#8  0x0000000000627dfc in mysql_execute_command (thd=0x2eea0c8) at /home/elenst/bzr/10.0/sql/sql_parse.cc:4851

#9  0x000000000062b026 in mysql_parse (thd=0x2eea0c8, rawbuf=0x7f3c6c0433e0 "alter table t1 add key if not exists (i)", length=40, parser_state=0x7f3c78a4e500) at /home/elenst/bzr/10.0/sql/sql_parse.cc:6154

#10 0x000000000061df6e in dispatch_command (command=COM_QUERY, thd=0x2eea0c8, packet=0x2eee3d9 "alter table t1 add key if not exists (i)", packet_length=40) at /home/elenst/bzr/10.0/sql/sql_parse.cc:1274

#11 0x000000000061d3e4 in do_command (thd=0x2eea0c8) at /home/elenst/bzr/10.0/sql/sql_parse.cc:983

#12 0x0000000000737da1 in do_handle_one_connection (thd_arg=0x2eea0c8) at /home/elenst/bzr/10.0/sql/sql_connect.cc:1267

#13 0x0000000000737af4 in handle_one_connection (arg=0x2eea0c8) at /home/elenst/bzr/10.0/sql/sql_connect.cc:1181

#14 0x00000000009c767b in pfs_spawn_thread (arg=0x2d652b8) at /home/elenst/bzr/10.0/storage/perfschema/pfs.cc:1800

#15 0x00007f3c8a3b8e9a in start_thread (arg=0x7f3c78a4f700) at pthread_create.c:308

#16 0x00007f3c896accbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112

revision-id: bar@mariadb.org-20130424142022-u4xhikvoqggze9b0

revno: 3745

branch-nick: 10.0