MDEV-8754 Wrong result for SELECT..WHERE year_field=2020 AND NULLIF(year_field,2010)='2020'
Problems:
1. Item_func_nullif stored a copy of args[0] in a private member m_args0_copy,
   which was invisible for the inherited Item_func menthods, like
   update_used_tables(). As a result, after equal field propagation
   things like Item_func_nullif::const_item() could return wrong result
   and a non-constant NULLIF() was erroneously treated as a constant
   at optimize_cond() time.
   Solution: removing m_args0_copy and storing the return value item
   in args[2] instead.
2. Equal field propagation did not work well for Item_fun_nullif.
   Solution: using ANY_SUBST for args[0] and args[1], as they are in
   comparison, and IDENTITY_SUBST for args[2], as it's not in comparison.

MDEV-8785 Wrong results for EXPLAIN EXTENDED...WHERE NULLIF(latin1_col, _utf8'a' COLLATE utf8_bin) IS NOT NULL

create a "preset" file to enable all encryption options at once

--encrypt-binlog and --encrypt-tmp-files used to mean
"encrypt XXX if encryption is available, otherwise don't encrypt",
now they mean "encrypt or fail with an error".

MDEV-8706 Wrong result for SELECT..WHERE time_column=TIMESTAMP'2015-08-30 00:00:00' AND time_column='00:00:00'

MDEV-8741 Equal field propagation leaves some remainders after simplifying WH ERE zerofill_column=2010 AND zerofill_column>=2010

(MDEV-8617: Post-fix for 10.1)
* Reset THD's PS members before returning when node is
not ready
* Add CF_SKIP_WSREP_CHECK flag to COM_STMT_XXX commands
* Skip TO replication of COM_STMT_PREPAREs for MyISAM
* Updated tests

Problem was -O2 and __attribute__((nonnull)) when it should have been
__attribute__((nonnull(1,2,3,4,5)))

Fixed unsafe reference to null pointer.

MDEV-8766 Wrong result for SELECT..WHERE LENGTH(time_column)=8 AND time_column=TIMESTAMP'2001-01-01 10:20:31'

remove old "to-be-implemented" definition of
the default-tmp-storage-engine option.

Added encryption support for online alter table where InnoDB temporary
files are used. Added similar support also for tables containing
full text-indexes.

Made sure that table remains encrypted during discard and import
tablespace.

MDEV-8699 Wrong result for SELECT..WHERE HEX(date_column)!='323030312D30312D3031' AND date_column='2001-01-01x'

The fix for MDEV-8749 also fixed MDEV-8742.
Just adding the test case from the bug report.

MDEV-8703 Wrong result for SELECT..WHERE LENGTH(decimal_10_1_column)!=3 AND decimal_10_1_column=1.10

Moving to field.cc.

Follow-up for MDEV-6066: new default value, the result file needs to be updated

Suppress errors about not being able to load plugins from file_key_management library.
Errors about the non-existing library are already suppressed globally.

New defaults for query cache caused wrong test output

removing IMPOSSIBLE_RESULT from Item_result, as it's not
needed any more. The fact that an Item is not in a comparison
context is now always designated by IDENTITY_SUBST in Subst_constraint.
Previously IMPOSSIBLE_RESULT and IDENTITY_SUBST co-existed but
actually meant the same thing.

MDEV-8747 Wrong result for SELECT..WHERE derived_table_column='a' AND derived_table_column<>_latin1'A' COLLATE latin1_bin
MDEV-8749 Wrong result for SELECT..WHERE derived_table_enum_column='number' AND derived_table_enum_column OP number

MDEV-8753: 10.1 build is broken: xtradb/handler/ha_innodb.cc:21430: error: redefinition of 'void ib_push_warning(trx_t*, ulint, const char*, ...)'

Fixed bad merge.

Analysis: Server tried to continue reading tablespace using a cursor after
we had resolved that pages in the tablespace can't be decrypted.

Fixed by addind check is tablespace still encrypted.

   MDEV-8588: Assertion failure in file ha_innodb.cc line 21140 if at least one encrypted table exists and encryption service is not available

    Analysis: Problem was that in fil_read_first_page we do find that
    table has encryption information and that encryption service
    or used key_id is not available. But, then we just printed
    fatal error message that causes above assertion.

    Fix: When we open single table tablespace if it has encryption
    information (crypt_data) store this crypt data to the table
    structure. When we open a table and we find out that tablespace
    is not available, check has table a encryption information
    and from there is encryption service or used key_id is not available.
    If it is, add additional warning for SQL-layer.

MDEV-8588: Assertion failure in file ha_innodb.cc line 21140 if at least one encrypted table exists and encryption service is not available

Analysis: Problem was that in fil_read_first_page we do find that
table has encryption information and that encryption service
or used key_id is not available. But, then we just printed
fatal error message that causes above assertion.

Fix: When we open single table tablespace if it has encryption
information (crypt_data) store this crypt data to the table
structure. When we open a table and we find out that tablespace
is not available, check has table a encryption information
and from there is encryption service or used key_id is not available.
If it is, add additional warning for SQL-layer.

cosmetic fixes. test fixes.

MDEV-6066: Merge new defaults from 5.6 and 5.7 (defaults changed, QC can be stopped with no-zero size)