MDEV-4514 After increasing user name length mysql.db is reported broken and...

MDEV-4514 After increasing user name length mysql.db is reported broken and event scheduler does not start

mysql-test/r/grant_4332.result

-set global event_scheduler = on;
 select user();
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
 def					user()	253	77	14	N	1	31	8
@@ -13,7 +12,7 @@ alter table mysql.columns_priv modify User char(80) binary not null default '';
 alter table mysql.procs_priv modify User char(80) binary not null default '';
 alter table mysql.proc modify definer char(141) collate utf8_bin not null default '';
 alter table mysql.event modify definer char(141) collate utf8_bin not null default '';
-flush privileges;
+set global event_scheduler = on;
 select user();
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
 def					user()	253	141	14	N	1	31	8

mysql-test/t/grant_4332.test

@@ -8,8 +8,6 @@
 
 --source include/not_embedded.inc
 
-set global event_scheduler = on;
-
 --enable_metadata
 select user();
 --disable_metadata
@@ -24,7 +22,10 @@ alter table mysql.columns_priv modify User char(80) binary not null default '';
 alter table mysql.procs_priv modify User char(80) binary not null default '';
 alter table mysql.proc modify definer char(141) collate utf8_bin not null default '';
 alter table mysql.event modify definer char(141) collate utf8_bin not null default '';
-flush privileges;
+
+--source include/restart_mysqld.inc
+
+set global event_scheduler = on;
 
 --enable_metadata
 select user();

sql/sql_acl.cc

@@ -70,7 +70,7 @@ TABLE_FIELD_TYPE mysql_db_table_fields[MYSQL_DB_FIELD_COUNT] = {
   }, 
   {
     { C_STRING_WITH_LEN("User") },
-    { C_STRING_WITH_LEN("char(16)") },
+    { C_STRING_WITH_LEN("char(") },
     {NULL, 0}
   },
   {