This came with the upgrade from yassl 2.3.0 to 2.3.4 -
ssl tests started to hang on Windows. Comparing and removing changes
I've got to this:

 void input_buffer::set_current(uint i) 
 {
-    if (i)
-        check(i - 1, size_); 
-    current_ = i; 
+    if (error_ == 0 && i && check(i - 1, size_) == 0)
+        current_ = i;
+    else
+        error_ = -1;
 }

in 2.3.0 i==0 was only used to avoid the check, in 2.3.4 it's an error.
but there are places in the code that do set_current(0) and others that
do, like, { before=get_current(); ...; set_current(before); } - and the
initial value of current_ is 0.

So, I suspect that set_current(0) should not be an error, but it should
only skip the check().

followup:
* explicitly disable SSLv2 and SSLv3, keep other protocols enabled
* fix a compiler warning
* rename the test and combinations to avoid confusion

vio/viossl.c:
  fix a compiler warning

innodb_stats_sample_pages

Analysis: If you set the number of analyzed pages 
to very low number compared to actual pages on 
that table/index it randomly pics those pages 
(default 8 pages), this leads to fact that query 
after analyze table returns different results. If 
the index tree is small, smaller than 10 * 
n_sample_pages + total_external_size, then the 
estimate is ok. For bigger index trees it is 
common that we do not see any borders between 
key values in the few pages we pick. But still 
there may be n_sample_pages different key values, 
or even more. And it just tries to 
approximate to n_sample_pages (8).

Fix: (1) Introduced new dynamic configuration variable
innodb_stats_sample_traditional  that retains
the current design. Default false.

(2) If traditional sample is not used we use
n_sample_pages = max(min(srv_stats_sample_pages,
                         index->stat_index_size),
                     log2(index->stat_index_size)*
                          srv_stats_sample_pages);

(3) Introduced new dynamic configuration variable
stat_modified_counter (default = 0) if set
sets lower bound for row updates when statistics is re-estimated.

If user has provided upper bound for how many rows needs to be updated
before we calculate new statistics we use minimum of provided value
and 1/16 of table every 16th round. If no upper bound is provided
(srv_stats_modified_counter = 0, default) then calculate new statistics
if 1 / 16 of table has been modified
since the last time a statistics batch was run.
We calculate statistics at most every 16th round, since we may have
a counter table which is very small and updated very often.
@param t table
@return true if the table has changed too much and stats need to be
recalculated
*/
#define DICT_TABLE_CHANGED_TOO_MUCH(t) \
	((ib_int64_t) (t)->stat_modified_counter > (srv_stats_modified_counter ? \
	ut_min(srv_stats_modified_counter, (16 + (t)->stat_n_rows / 16)) : \
		16 + (t)->stat_n_rows / 16))

The bug was that full memory barrier was missing in the code that ensures that
a waiter on an InnoDB mutex will not go to sleep unless it is guaranteed to be
woken up again by another thread currently holding the mutex. This made
possible a race where a thread could get stuck waiting for a mutex that is in
fact no longer locked. If that thread was also holding other critical locks,
this could stall the entire server. There is an error monitor thread than can
break the stall, it runs about once per second. But if the error monitor
thread itself got stuck or was not running, then the entire server could hang
infinitely.

This was introduced on i386/amd64 platforms in 5.5.40 and 10.0.13 by an
incorrect patch that tried to fix the similar problem for PowerPC.

This commit reverts the incorrect PowerPC patch, and instead implements a fix
for PowerPC that does not change i386/amd64 behaviour, making PowerPC work
similarly to i386/amd64.

change SSL methods to be SSLv23 (according to openssl manpage:
"A TLS/SSL connection established with these methods may understand
the SSLv2, SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols") from
TLSv1 methods, that go back to the initial SSL implementation
in MySQL in 2001.

OpenSSL default ciphers are different if TLSv1.2 is enabled,
so tests need to take this into account.

e.g. from "error:00000001:lib(0):func(0):reason(1)"
to "error:140830B5:SSL routines:SSL3_CLIENT_HELLO:no ciphers available"

two bugs in mysql_config:
1. flags like -Werror=format were not stipped out
2. one-pass s/// command was used that could not remove all matching flags
   (e.g. s/ A */ /g cannot remove all A's in " 1 2 A A A A A 4 5 ")

MDEV-4513 Valgrind warnings (Conditional jump or move depends on uninitialised value) in inflate on UNCOMPRESS

MDEV-6789 segfault in Item_func_from_unixtime::get_date on updating table with virtual columns

* prohibit VALUES in partitioning expression
* prohibit user and system variables in virtual column expressions
* fix Item_func_date_format to cache locale (for %M/%W to return the same as MONTHNAME/DAYNAME)
* fix Item_func_from_unixtime to cache time_zone directly, not THD (and not to crash)
* added tests for other incorrectly allowed (in vcols) functions to see that they don't crash

MDEV-3940 Server crash or assertion `item->type() == Item::STRING_ITEM' failure on LOAD DATA through a view with statement binary logging

A "field" could be either an Item_field or
(if loading into a view) an Item_direct_ref that references Item_field.

Also: when iterating fields, use fields of the TABLE_LIST (table or view),
not fields of a TABLE (actual underlying table - might have more columns).

  Fixed the case when a polygon contains a single-point ring.

Backport to 5.3:
- Don't call index_reader->interrupt_read() if the
  index reader has returned all rows that matched its keys.

only enforce the include order if SAFE_MUTEX is defined
(that is, in MariaDB source builds in debug mode)

When parsing a field declaration, grab type information from LEX before it's overwritten
by further rules. Pass type information through the parser stack to the rule that needs it.

The test complains that the server failed to disappear upon shutdown /
wait_for_disconnect. Trying to solve the probably race condition by 
adding a wait before restart.

Excluding ORDER BY condition should be done after preparation it (even to catch syntax errors).

- Don't call index_reader->interrupt_read() if the
  index reader has returned all rows that matched its keys.

Analysis: InnoDB error monitor is responsible to call every second
sync_arr_wake_threads_if_sema_free() to wake up possible hanging 
threads if they are missed in mutex_signal_object. This is not 
possible if error monitor itself is on mutex/semaphore wait. We 
should avoid all unnecessary mutex/semaphore waits on error monitor.
Currently error monitor calls function buf_flush_stat_update() 
that calls log_get_lsn() function and there we will try to get 
log_sys mutex. Better, solution for error monitor is that in 
buf_flush_stat_update() we will try to get lsn with 
mutex_enter_nowait() and if we did not get mutex do not update 
the stats.

Fix: Use log_get_lsn_nowait() function on buf_flush_stat_update()
function. If returned lsn is 0, we do not update flush stats. 
log_get_lsn_nowait() will use mutex_enter_nowait() and if
we get mutex we return a correct lsn if not we return 0.

The test case had a classic mistake: SET DEBUG_SYNC='now SIGNAL xxx'
followed immediately by SET DEBUG_SYNC='RESET'. This makes it
possible for the waiter to miss the signal, if it does not manage
to wake up prior to the RESET.

MDEV-7089: Test failures in main.failed_auth_unixsocket and plugins.unix_socket depending on environment

The test cases had some --replace_result $USER USER. The problem is that the
value of $USER can be anything, depending on the name of the unix account that
runs the test suite. So random parts of the result can be errorneously
replaced, causing test failures.

Fix by making the replacements more specific, so they will match only the
intended stuff regardless of the value of $USER.

Merging a fix from the upstream.