MDEV-30154: Assertion `strcasecmp(rolename, public_name.str) || acl_public == role' failed in acl_update_role on GRANT ... TO PUBLIC

Reset of acl_public was made too early (before saving it to restore in case
of error).

Author: sanja-byelkin

mysql-test/main/public_basic.result

@@ -100,6 +100,23 @@ delete from mysql.global_priv where user="PUBLIC";
 flush privileges;
 grant execute on procedure mtr.add_suppression to public;
 revoke execute on procedure mtr.add_suppression from public;
+#
+# MDEV-30154: Assertion `strcasecmp(rolename, public_name.str) ||
+# acl_public == role' failed in acl_update_role on GRANT ... TO PUBLIC
+#
+call mtr.add_suppression("Can't open and lock privilege tables");
+USE test;
+GRANT SELECT ON *.* TO PUBLIC;
+LOCK TABLES mysql.time_zone WRITE,mysql.proc WRITE;
+FLUSH PRIVILEGES;
+ERROR HY000: Table 'db' was not locked with LOCK TABLES
+LOCK TABLE nonexisting WRITE;
+ERROR 42S02: Table 'test.nonexisting' doesn't exist
+GRANT SELECT ON *.* TO PUBLIC;
+REVOKE SELECT ON *.* FROM PUBLIC;
+#
+# End of 10.11 test
+#
 # clean up
 delete from mysql.global_priv where user="PUBLIC";
 flush privileges;

mysql-test/main/public_basic.test

@@ -109,6 +109,26 @@ flush privileges;
 grant execute on procedure mtr.add_suppression to public;
 revoke execute on procedure mtr.add_suppression from public;
 
+--echo #
+--echo # MDEV-30154: Assertion `strcasecmp(rolename, public_name.str) ||
+--echo # acl_public == role' failed in acl_update_role on GRANT ... TO PUBLIC
+--echo #
+call mtr.add_suppression("Can't open and lock privilege tables");
+USE test;
+GRANT SELECT ON *.* TO PUBLIC;
+LOCK TABLES mysql.time_zone WRITE,mysql.proc WRITE;
+--error 1100
+FLUSH PRIVILEGES;
+--error 1146
+LOCK TABLE nonexisting WRITE;
+GRANT SELECT ON *.* TO PUBLIC;
+
+REVOKE SELECT ON *.* FROM PUBLIC;
+
+--echo #
+--echo # End of 10.11 test
+--echo #
+
 -- echo # clean up
 delete from mysql.global_priv where user="PUBLIC";
 flush privileges;

sql/sql_acl.cc

@@ -2918,7 +2918,6 @@ bool acl_reload(THD *thd)
   int result;
   DBUG_ENTER("acl_reload");
 
-  acl_public= NULL;
 
   Grant_tables tables;
   /*
@@ -2963,6 +2962,7 @@ bool acl_reload(THD *thd)
   old_mem= acl_memroot;
   delete_dynamic(&acl_wild_hosts);
   my_hash_free(&acl_check_hosts);
+  acl_public= NULL;
 
   if ((result= acl_load(thd, tables)))
   {					// Error. Revert to old list