Switch to utf8mb4 as default character set.

This applies only for new databases and tables, so should be safe.
WordPress and many other apps already assume utf8mb4 as the default.

debian/additions/mariadb.conf.d/client.cnf

 [client]
 # Default is Latin1, if you need UTF-8 set this (also in server section)
-default-character-set = utf8
+default-character-set = utf8mb4
+
+[mysql]
+default-character-set = utf8mb4
+

debian/additions/mariadb.conf.d/mysqld.cnf

@@ -85,12 +85,15 @@ max_binlog_size   = 100M
 #
 # * Character sets
 #
-# Default is Latin1, if you need UTF-8 set all this (also in client section)
-#
-character-set-server  = utf8
-collation-server      = utf8_general_ci
-character_set_server   = utf8
-collation_server       = utf8_general_ci
+# MySQL/MariaDB default is Latin1, but in Debian we rather default to the full 
+# utf8 4-bit character set. See also client.cnf
+#
+character-set-server  = utf8mb4
+collation-server      = utf8mb4_general_ci
+character_set_server   = utf8mb4
+collation_server       = utf8mb4_general_ci
+init-connect='SET NAMES utf8mb4'
+
 
 #
 # * Unix socket authentication plugin

debian/changelog

@@ -3,6 +3,7 @@ mariadb-10.0 (10.0.20-2) unstable; urgency=low
   * Fix bash test logic in postinstall (Closes: #789589)
   * Add extra sort in d/rules mysqld.sym.gz command to satisfy Debian
     reproducible build requirements
+  * Switch to utf8mb4 as default character set
 
  -- Otto Kekäläinen <otto@seravo.fi>  Fri, 03 Jul 2015 17:11:01 +0300