Activation generates unexpected output

When installing, there is an unexpected output error if $wpdb->has_cap(‘collation’) is true. This is the result of an undefined variable ($collation). The following block in install.pipes.php lines 35-42 is the issue:

if ( $wpdb->has_cap( 'collation' ) ) {
	if ( ! empty( $wpdb->charset ) ) {
		$collation .= "DEFAULT CHARACTER SET $wpdb->charset";
	}
	if ( ! empty( $wpdb->collate ) ) {
		$collation .= " COLLATE $wpdb->collate";
	}
}

The problem is that the variable $collation is not defined when you append to it using the concatenating assignment operator “.=”

If debug is turned on (or PHP notices are enabled), this generates an error on activation.

$collation should be declared prior to this block, such as:

$collation = '';

OR, don’t concatenate an undefined variable:

if ( $wpdb->has_cap( 'collation' ) ) {
	if ( ! empty( $wpdb->charset ) ) {
		$collation = "DEFAULT CHARACTER SET $wpdb->charset";
	}
	if ( ! empty( $wpdb->collate ) ) {
		$collation = " COLLATE $wpdb->collate";
	}
}