Steps to reproduce

1. Create a table with a field type TIMESTAMP ON DEFAULT CURRENT_TIMESTAMP

CREATE TABLE t (id int NOT NULL UNIQUE AUTO_INCREMENT, 
                              name VARCHAR(30), 
                               ts TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP);

2. Go to Insert tab on phpmyadmin interface
3. Check default value for TIMESTAMP field is current_timestamp().000000
4. Click GO

Expected behaviour

Insert the row with the current date and time

Actual behaviour

Inserts the row with 0000-00-00 00:00:00 on the timestamp field, and shows a warning message in red:

Warning: #1265 Data truncated for column 'ts' at row 1

Server configuration

Operating system: Debian jessie

Web server: Apache 2.4

Database: mariaDB 10.2

PHP version: php7.1

phpMyAdmin version: 4.7.7

Client configuration

Browser: Firefox 57.0.4

Operating system: Ubuntu xenial