Connector/NET does not expect collation IDs returned by "show collations"
to be NULL, runs into an exception.
The fix is to determine connector/net using its connection attributes,
then make sure "show collations" does not output NULL IDs.
The patch introduces new old_mode NO_NULL_COLLATION_IDs, that is
automatically set, once MySQL Connector/NET connection is determined.
A test was added, that uses MySql.Data from powershell - only works
if MySql.Data is installed into GAC (i.e with C/NET MSI package)
post-merge fixes:
* remove log_slow_queries_not_using_indexes, no need to create variables
that are deprecated since the moment of creation
* rename log_slow_query_enable->log_slow_query
no other variable uses *_enable pattern
* MDEV-29626 Assertion `self == &Sys_slow_query_log' failed in fix_log_state
* tests
Closes#2137
Thus, all these variables will be
grouped together and more logically named.
Descriptions for the old variables were updated to indicate they are
now aliases for the newly introduced variables with prefix log_slow.
log_slow_queries_not_using_indexes_filter will not be addressed
in this merge request.
log_throttle_queries_not_using_indexes seems to no longer be in use.
MTR tests are also updated to include the new variable names.
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.
