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().

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))

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

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.

in mysql_upgrade: do FLUSH PRIVILEGES at the end, not together with
mysql_fix_privilege_tables

mysql-test/t/mysql_upgrade-6984.opt:
  use a dummy second option to force server restart after the test

skip qsort if the sort key has zero length

* use the same HAVE_C/CXX_ variables for compiler flag tests as the rest of
  the server and tokudb - to use cached results
* plugin's name should be "mroonga" not "ha_mroonga"
* don't use set_property(TARGET plugin_name ...), it aborts cmake when a plugin
  id disabled, because the target doesn't exists in that case

result: mroonga can now be disabled from cmake command line

try the first unique key as a surrogate PK *before* disabling extended
keys because of missing PK

1. remove find_mysql_client (from a bad merge)
2. use $mysql_command

disable binlogging when loading help tables

update mysql_system_tables_fix.sql to match mysql_system_tables.sql

use the same restriction for character_set_client on the command line
and from SQL.

Also: remove strange hack from thd_init_client_charset() that contradicted
the manual (collation_connection and character_set_result were not always set)

a different fix for view.test --ps-protocol crash
(revert the old fix that has caused a regression)

ALTER TABLE: don't fill default values per row, do it once.
And do it in two places - for copy_data_between_tables() and for online ALTER.

Also, run function_defaults test both for MyISAM and for InnoDB.

when reading data into the record buffer, the tail of the VARCHAR
(between real and max varchar length) is not written to. initialize the record
buffer to avoid writing uninitialized memory to disk.

update big test results

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.