The behavior that used to be triggered by EXPLAIN EXTENDED has been the
default for a long time and the previously deprecated EXTENDED keyword
was finally removed in MySQL 8.0.

To avoid breaking the spec on very old MySQL versions we just catch the
SQL syntax error and retry without the EXTENDED keyword.

The specs could fail if the /etc/mysql directory contained files that
cannot be read by the user running the specs, eg. debian.cnf.

Since we already specify :sslca, the :sslcapath option doesn't make any
sense and can stay at the system default value.

The default dist is currently trusty, so the travis install scripts that
imply the old default of precise no longer work properly.

A better solution would be to update to the trusty (unsupported) or
xenial (supported) environment, but this should be the most minimal
change to restore the previous CI behavior.

This reverts commit d572951 because
Travis CI updates rubygems with important security fixes.

which should allow to use the preinstalled 2.3.3 version.

because it can no longher be installed due to missing binaries.

See: http://binaries.rubini.us/index.txt

caused by failing bundler install during rvm use.

Also the 2.3 version should be preinstalled.

because the specs require certs from .travis_ssl.sh installed in
/etc/mysql which is inaccessible without root on macOS.

A more involved fix would be to parameterize the paths in the specs and
adapt the .travis_ssl.sh script to work properly on macOS.

The latest MySQL 5.7 versions ingore SSL options, if connecting over a
UNIX socket and ssl-mode=REQUIRED/VERIFY_CA/VERIFY_IDENTITY is not set.

Since the :ssl_mode option is not implemented in 0.3, the easierst
workaround is to force connection over TCP by using the loopback IP.

It appears that none of the tested MySQL versions require this anymore.

This is required to allow password-less auth as root for the $USER.

and fix bug, mapping them to "" instead of NULL.

* Remove hardcoded dist names from scripts, reduce dependencies
* Switch from deprecated precise to trusty dist
* Update SSL script to force SHA1 for MySQL 5.5 w/yaSSL on Trusty
* Update MySQL install script to support MySQL 5.6 & 8.0 install
* Fix MariaDB downgrade 5.6 -> 5.5 on Trusty (remove old data dir)
* Update MariaDB install script to use latest MariaDB 10.x (10.3)
* Add DB=mysql8 to build matrix
* Add DB=mysql55 to build matrix, since MySQL 5.6 is pre-installed

and enabling fast finish, because compiling ree from source takes much
longer than all other builds and errors in ree but not in 1.8.7 are
highly unlikely.