It is used in the out-of date Ubuntu 21.10 Impish.

The problem was earlier fixed by the patch for MDEV-30034.
Adding MTR tests only.

Spider system tables should be created so that wsrep_on=OFF.

Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

Query cache should be invalidated if we are not in applier. For some
reason this condition was incorrect starting from 10.5 but it is
correct in 10.4.

Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

- Adding a new argument "flag" to MY_COLLATION_HANDLER::strnncollsp_nchars()
  and a flag MY_STRNNCOLLSP_NCHARS_EMULATE_TRIMMED_TRAILING_SPACES.
  The flag defines if strnncollsp_nchars() should emulate trailing spaces
  which were possibly trimmed earlier (e.g. in InnoDB CHAR compression).
  This is important for NOPAD collations.

  For example, with this input:
   - str1= 'a '    (Latin letter a followed by one space)
   - str2= 'a  '   (Latin letter a followed by two spaces)
   - nchars= 3
  if the flag is given, strnncollsp_nchars() will virtually restore
  one trailing space to str1 up to nchars (3) characters and compare two
  strings as equal:
  - str1= 'a  '  (one extra trailing space emulated)
  - str2= 'a  '  (as is)

  If the flag is not given, strnncollsp_nchars() does not add trailing
  virtual spaces, so in case of a NOPAD collation, str1 will be compared
  as less than str2 because it is shorter.

- Field_string::cmp_prefix() now passes the new flag.
  Field_varstring::cmp_prefix() and Field_blob::cmp_prefix() do
  not pass the new flag.

- The branch in cmp_whole_field() in storage/innobase/rem/rem0cmp.cc
  (which handles the CHAR data type) now also passed the new flag.

- Fixing UCA collations to respect the new flag.
  Other collations are possibly also affected, however
  I had no success in making an SQL script demonstrating the problem.
  Other collations will be extended to respect this flags in a separate
  patch later.

- Changing the meaning of the last parameter of Field::cmp_prefix()
  from "number of bytes" (internal length)
  to "number of characters" (user visible length).

  The code calling cmp_prefix() from handler.cc was wrong.
  After this change, the call in handler.cc became correct.

  The code calling cmp_prefix() from key_rec_cmp() in key.cc
  was adjusted according to this change.

- Old strnncollsp_nchar() related tests in unittest/strings/strings-t.c
  now pass the new flag.
  A few new tests also were added, without the flag.

The tests innodb.import_tablespace_race, innodn.restart, and innodb.innodb-wl5522 move
the tablespace file between the data directory and the tmp directory specified by
global environment variables. However this is risky because it's not unusual that the
set tmp directory (often under /tmp) is mounted on another disk partition or device,
and 'move_file' command may fail with "Errcode: 18 'Invalid cross-device link.'"

For innodb.import_tablespace_race and innodb.innodb-wl5522, moving files
across directories is not necessary. Modify the tests so they rename
files under the same directory. For innodb.restart, instead of moving
between datadir and MYSQL_TMPDIR, move the files under MYSQLTEST_VARDIR.

All new code of the whole pull request, including one or several files that
are either new files or modified ones, are contributed under the BSD-new license.
I am contributing on behalf of my employer Amazon Web Services, Inc.

The tests innodb.import_tablespace_race, innodn.restart, and innodb.innodb-wl5522 move
the tablespace file between the data directory and the tmp directory specified by
global environment variables. However this is risky because it's not unusual that the
set tmp directory (often under /tmp) is mounted on another disk partition or device,
and 'move_file' command may fail with "Errcode: 18 'Invalid cross-device link.'"

To stabilize mysqltest in the described scenario, and prevent such
behavior in the future, let make_file() check both from file path and to
file path and make sure they are either both under MYSQLTEST_VARDIR or
MYSQL_TMP_DIR.

All new code of the whole pull request, including one or several files that
are either new files or modified ones, are contributed under the BSD-new license.
I am contributing on behalf of my employer Amazon Web Services, Inc.