Fix tests for pt-table-sync

$ prove -vw --trap --timer t/pt-table-sync
[19:48:24] t/pt-table-sync/basics.t ................... 
1..24
ok 1 - It dislikes changing a slave
ok 2 - No alg sync
ok 3 - Synced OK with no alg
ok 4 - Basic Stream sync
ok 5 - Synced OK with Stream
ok 6 - Basic GroupBy sync
ok 7 - Synced OK with GroupBy
ok 8 - Basic Chunk sync
ok 9 - Synced OK with Chunk
ok 10 - Basic Chunk sync
ok 11 - Synced OK with --slave-user
ok 12 - Basic Nibble sync
ok 13 - Synced OK with Nibble
ok 14 - Nibble with transactions and locking
ok 15 - Synced OK with Nibble
ok 16 - Found the first row
ok 17 - Found the second row
ok 18 - Right number of rows to update
ok 19 - Synced with Nibble and data-size chunksize
ok 20 - --replicate with char index col (bug 911996)
ok 21 - Synced diff (bug 911996)
not ok 22 - --replicate with uc index (bug 927771)

#   Failed test '--replicate with uc index (bug 927771)'
#   at t/pt-table-sync/basics.t line 242.
#                   'Incorrect datetime value: '0000-00-00 00:00:00' for column 'Timestamp' at row 1 ...
...
# Table 't' was not locked with LOCK TABLES [for Statement "SELECT MIN(`id`), MAX(`id`) FROM `test`.`t` FORCE INDEX (`PRIMARY`)"] at line 4293 while doing test.t on 127.1
# '
#     doesn't match '(?^:REPLACE INTO `test`.`t`\(`id`, `c`\) VALUES \('9', 'i'\))'
not ok 23 - Synced slaved (bug 927771)

#   Failed test 'Synced slaved (bug 927771)'
#   at t/pt-table-sync/basics.t line 250.
#     Structures begin differing at:
#          $got->[0][1] = 'z'
#     $expected->[0][1] = 'i'
ok 24 - Sandbox servers
# Looks like you failed 2 tests of 24.
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/24 subtests 
...
# Table 't' was not locked with LOCK TABLES [for Statement "SELECT MIN(`id`), MAX(`id`) FROM `test`.`t` FORCE INDEX (`PRIMARY`)"] at line 4293 while doing test.t on 127.1
# '
#     doesn't match '(?^:REPLACE INTO `test`.`t`\(`id`, `c`\) VALUES \('9', 'i'\))'
not ok 23 - Synced slaved (bug 927771)

#   Failed test 'Synced slaved (bug 927771)'
#   at t/pt-table-sync/basics.t line 250.
#     Structures begin differing at:
#          $got->[0][1] = 'z'
#     $expected->[0][1] = 'i'
ok 24 - Sandbox servers
# Looks like you failed 2 tests of 24.
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/24 subtests