PT-2154 - Fix tests for pt-table-sync

- Removed junk comment from t/pt-table-sync/pt-2309.t
- Re-enabled t/pt-table-sync/issue_96.t in 8.0+
- Re-enabled tests in t/pt-table-sync/pt-1256.t in 8.0.14+
- Re-enabled t/pt-table-sync/master_master.t in 8.0+
- Re-enabled t/pt-table-sync/lock_and_rename.t in 8.0+
- Re-enabled t/pt-table-sync/issue_965.t
- Added proper disable comments into t/pt-table-sync/issue_920.t and t/pt-table-sync/issue_996.t

t/pt-table-sync/issue_996.t

@@ -0,0 +1,118 @@
+#!/usr/bin/env perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use PerconaTest;
+use Sandbox;
+require "$trunk/bin/pt-table-sync";
+
+my $dp = new DSNParser(opts=>$dsn_opts);
+my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+my $master_dbh = $sb->get_dbh_for('master');
+my $slave_dbh  = $sb->get_dbh_for('slave1'); 
+
+if ( !$master_dbh ) {
+   plan skip_all => 'Cannot connect to sandbox master';
+}
+elsif ( !$slave_dbh ) {
+   plan skip_all => 'Cannot connect to sandbox slave';
+}
+elsif ( $sandbox_version ge '8.0' ) {
+   plan skip_all => 'Test fails due to https://bugs.mysql.com/bug.php?id=115017';
+}
+else {
+   plan tests => 3;
+}
+
+my $output;
+my @args = ('--sync-to-master', 'h=127.1,P=12346,u=msandbox,p=msandbox',
+            qw(-d issue_375 --replicate issue_375.checksums --print));
+my $pt_table_checksum = "$trunk/bin/pt-table-checksum h=127.1,P=12345,u=msandbox,p=msandbox -d issue_375 --chunk-size 20 --chunk-size-limit 0 --set-vars innodb_lock_wait_timeout=3";
+
+# #############################################################################
+# Issue 996: might not chunk inside of pt-table-checksum's boundaries
+# #############################################################################
+
+# Re-using this table for this issue.  It has 100 pk rows.
+$sb->load_file('master', 't/pt-table-sync/samples/issue_375.sql');
+wait_until(
+   sub {
+      my $row;
+      eval {
+         $row = $slave_dbh->selectrow_hashref("select * from issue_375.t where id=35");
+      };
+      return 1 if $row && $row->{foo} eq 'ai';
+   },
+);
+
+# Make the tables differ.  These diff rows are all in chunk 1.
+$slave_dbh->do("update issue_375.t set foo='foo' where id in (21, 25, 35)");
+wait_until(
+   sub {
+      my $row;
+      eval {
+         $row = $slave_dbh->selectrow_hashref("select * from issue_375.t where id=35");
+      };
+      return 1 if $row && $row->{foo} eq 'foo';
+   },
+   0.5, 10,
+);
+
+# pt-table-checksum the table with 5 chunks of 20 rows.
+$output = `$pt_table_checksum --replicate issue_375.checksums`;
+is(
+   PerconaTest::count_checksum_results($output, 'diffs'),
+   1,
+   "Chunk checksum diff"
+);
+
+diag(`/tmp/12346/use -e "analyze table issue_375.t"`);
+diag(`/tmp/12345/use -e "EXPLAIN SELECT * FROM issue_375.t FORCE INDEX (PRIMARY) WHERE ((id >= '21')) AND ((id <= '40'))"`);
+diag(`/tmp/12345/use -e "SELECT * FROM issue_375.t FORCE INDEX (PRIMARY) WHERE ((id >= '21')) AND ((id <= '40'))"`);
+diag(`/tmp/12345/use -e "EXPLAIN ANALYZE SELECT * FROM issue_375.t FORCE INDEX (PRIMARY) WHERE ((id >= '21')) AND ((id <= '40'))"`);
+# Run pt-table-sync with the replicate table.  Chunk size here is relative
+# to the pt-table-checksum ranges.  So we sub-chunk the 20 row ranges into
+# 4 5-row sub-chunks.
+my $file = "/tmp/mts-output.txt";
+output(
+   sub { pt_table_sync::main(@args, qw(--chunk-size 5 -v -v)) },
+   file => $file,
+   stderr => 1,
+);
+
+# The output shows that the 20-row range was chunked into 4 5-row sub-chunks.
+$output = `cat $file | grep 'AS chunk_num' | cut -d' ' -f3,4`;
+is(
+   $output,
+"/*issue_375.t:1/5*/ 0
+/*issue_375.t:1/5*/ 0
+/*issue_375.t:2/5*/ 1
+/*issue_375.t:2/5*/ 1
+/*issue_375.t:3/5*/ 2
+/*issue_375.t:3/5*/ 2
+/*issue_375.t:4/5*/ 3
+/*issue_375.t:4/5*/ 3
+/*issue_375.t:5/5*/ 4
+/*issue_375.t:5/5*/ 4
+",
+   "Chunks within chunk"
+);
+diag(`cat $file`);
+
+diag(`rm -rf $file >/dev/null`);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($master_dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+exit;