add failing test for #290, invalid utf8 char

this test assumes a latin1-encoded table with content containing bytes
in the \x80-\xFF, which are invalid single-byte characters in utf8 and
cannot be inserted in the altered table when the column containing these
characters is changed to utf8(mb4).

since these characters cannot be inserted, gh-ost fails.

localtests/latin1text-to-utf8mb4/create.sql

@@ -0,0 +1,24 @@
+drop table if exists gh_ost_test;
+create table gh_ost_test (
+  id int auto_increment,
+  t text charset latin1 collate latin1_swedish_ci,
+  primary key(id)
+) auto_increment=1 charset latin1 collate latin1_swedish_ci;
+
+insert into gh_ost_test values (null, char(128));
+
+drop event if exists gh_ost_test;
+delimiter ;;
+create event gh_ost_test
+  on schedule every 1 second
+  starts current_timestamp
+  ends current_timestamp + interval 60 second
+  on completion not preserve
+  enable
+  do
+begin
+  insert into gh_ost_test values (null, md5(rand()));
+  insert into gh_ost_test values (null, char(128));
+  update gh_ost_test set t=char(230) order by id desc limit 1;
+  delete from gh_ost_test where t=char(230);
+end ;;

localtests/latin1text-to-utf8mb4/extra_args

@@ -0,0 +1 @@
+--alter "convert to character set utf8mb4 collate utf8mb4_unicode_ci"

localtests/latin1text-to-utf8mb4/ignored_versions

@@ -0,0 +1 @@
+(5.5)