MDEV-13912 mysql_upgrade: case (in)sensitivity for stored procedures

mysql_upgrade used to convert all columns of mysql.db to
utf8_general_ci and then back to utf8_bin. In two separate ALTER's.

This failed if UNIQUE indexes in mysql.db contained entries
that differ only in the letter case.

mysql-test/r/lowercase_fs_off.result

@@ -63,3 +63,44 @@ CREATE TRIGGER t1_bi BEFORE INSERT ON t1 FOR EACH ROW SET new.a= 1;
 RENAME TABLE t1 TO T1;
 ALTER TABLE T1 RENAME t1;
 DROP TABLE t1;
+create database TEST;
+create procedure TEST.pr() begin end;
+create procedure test.pr() begin end;
+Phase 1/4: Fixing views
+Phase 2/4: Fixing table and database names
+Phase 3/4: Checking and upgrading tables
+Processing databases
+information_schema
+TEST
+mtr
+mtr.global_suppressions                            OK
+mtr.test_suppressions                              OK
+mysql
+mysql.columns_priv                                 OK
+mysql.db                                           OK
+mysql.event                                        OK
+mysql.func                                         OK
+mysql.help_category                                OK
+mysql.help_keyword                                 OK
+mysql.help_relation                                OK
+mysql.help_topic                                   OK
+mysql.host                                         OK
+mysql.ndb_binlog_index                             OK
+mysql.plugin                                       OK
+mysql.proc                                         OK
+mysql.procs_priv                                   OK
+mysql.proxies_priv                                 OK
+mysql.servers                                      OK
+mysql.tables_priv                                  OK
+mysql.time_zone                                    OK
+mysql.time_zone_leap_second                        OK
+mysql.time_zone_name                               OK
+mysql.time_zone_transition                         OK
+mysql.time_zone_transition_type                    OK
+mysql.user                                         OK
+performance_schema
+test
+Phase 4/4: Running 'mysql_fix_privilege_tables'
+OK
+drop procedure test.pr;
+drop database TEST;

mysql-test/t/lowercase_fs_off.test

@@ -102,3 +102,13 @@ CREATE TRIGGER t1_bi BEFORE INSERT ON t1 FOR EACH ROW SET new.a= 1;
 RENAME TABLE t1 TO T1;
 ALTER TABLE T1 RENAME t1;
 DROP TABLE t1;
+
+#
+# MDEV-13912 mysql_upgrade: case (in)sensitivity for stored procedures
+#
+create database TEST;
+create procedure TEST.pr() begin end;
+create procedure test.pr() begin end;
+--exec $MYSQL_UPGRADE --force 2>&1
+drop procedure test.pr;
+drop database TEST;

scripts/mysql_system_tables_fix.sql

@@ -468,15 +468,15 @@ ALTER TABLE proc MODIFY name char(64) DEFAULT '' NOT NULL,
                  DEFAULT CHARACTER SET utf8;
 
 # Correct the character set and collation
-ALTER TABLE proc CONVERT TO CHARACTER SET utf8;
 # Reset some fields after the conversion
 SET @alter_statement = CONCAT("
-ALTER TABLE proc  MODIFY db
-                         char(64) collate utf8_bin DEFAULT '' NOT NULL,
+ALTER TABLE proc CONVERT TO CHARACTER SET utf8,
+                  MODIFY db
+                         char(64) binary DEFAULT '' NOT NULL,
                   MODIFY definer
-                         char(", @definer_name_length, ") collate utf8_bin DEFAULT '' NOT NULL,
+                         char(", @definer_name_length, ") binary DEFAULT '' NOT NULL,
                   MODIFY comment
-                         char(64) collate utf8_bin DEFAULT '' NOT NULL
+                         char(64) binary DEFAULT '' NOT NULL
 ");
 PREPARE alter_stmt FROM @alter_statement;
 EXECUTE alter_stmt;