See also bug 11775312, all queries listed there now have the
same results here, as they have in 5.1

This assumption in Item_cache_datetime::cache_value_int
was wrong:
-  /* Assume here that the underlying item will do correct conversion.*/
-  int_value= example->val_int_result();

The problem was that Item_sum_hybrid::val_xxx() did not propagate null values
up the expression tree.

"set optimizer_switch to e or d causes invalid memory writes/valgrind warnings":
due to prefix support, the argument "e" was overwritten with its full value
"engine_condition_pushdown", which caused a buffer overrun.
This was wrong usage of find_type(); other wrong usages are fixed here too.
Please start reading with the comment of typelib.c.

The crash happens because Item_cache which is result
holder for Item_subselect can't correctly convert
a DATETIME value from string to int representation.
The fix is to disable constant item convertion for
subselect(partial rollback of bug52157 fix).

An after-fix to workaround different metadata in "mtr --ps" output.

batch_readline_init() was modified - make check for 
type of file for input stream unless target platform
is WINDOWS since on this platform S_IFBLK is undefined.

Reverse DNS lookup of "localhost" returns "broadcasthost" on Snow Leopard (Mac), and NULL on most others.
Simply ignore the output, as this is not an essential part of UDF testing.

batch_readline_init() was modified - return an error
if the input source is a directory or a block device.

This follow-up is necessary because on some platforms,
such as Solaris, call to read() from directory may be
successful.

Resolved an innodb conflict thanks to vasil.

Test failed on a certain Linux platform in automated environment. It turns out that this platform has an old version of Perl modules DBI and DBD::mysql installed, as well as the OS itself being relatively old.
Allowing error code 11 to be returned from mysqlhotcopy on expected error seems harmless and will make the test pass also with older libraries.