don't consider the password "expired" if authentication is passwordless

mysql-test/main/password_expiration_unix_socket.test

@@ -0,0 +1,24 @@
+#
+# Test password expiration
+#
+
+--source include/not_embedded.inc
+--source include/have_unix_socket.inc
+
+--echo #
+--echo # A password cannot expire, if there is no password
+--echo #
+
+--let $replace=create user $USER
+--replace_result $replace "create user USER"
+--eval create user $USER identified via unix_socket
+
+--let $replace=alter user $USER
+--replace_result $replace "alter user USER"
+--eval alter user $USER password expire
+
+--exec $MYSQL -u $USER -e 'select 1'
+
+--let $replace=drop user $USER
+--replace_result $replace "drop user USER"
+--eval drop user $USER