branches/5.1:

Followup to r4575 and the fix of Bug#43309 Test main.innodb can't be run twice:

Add an explanatory comment, as suggested by Patrick Crews in the bug report.

mysql-test/innodb.test

@@ -15,10 +15,14 @@
 
 -- source include/have_innodb.inc
 
-#
-# Small basic test with ignore
-#
-
+# Save the original values of some variables in order to be able to
+# estimate how much they have changed during the tests. Previously this
+# test assumed that e.g. rows_deleted is 0 here and after deleting 23
+# rows it expected that rows_deleted will be 23. Now we do not make
+# assumptions about the values of the variables at the beginning, e.g.
+# rows_deleted should be 23 + "rows_deleted before the test". This allows
+# the test to be run multiple times without restarting the mysqld server.
+# See Bug#43309 Test main.innodb can't be run twice
 -- disable_query_log
 SET @innodb_thread_concurrency_orig = @@innodb_thread_concurrency;
 
@@ -37,6 +41,10 @@ drop table if exists t1,t2,t3,t4;
 drop database if exists mysqltest;
 --enable_warnings
 
+#
+# Small basic test with ignore
+#
+
 create table t1 (id int unsigned not null auto_increment, code tinyint unsigned not null, name char(20) not null, primary key (id), key (code), unique (name)) engine=innodb;
 
 insert into t1 (code, name) values (1, 'Tim'), (1, 'Monty'), (2, 'David'), (2, 'Erik'), (3, 'Sasha'), (3, 'Jeremy'), (4, 'Matt');