<?php

// See http://core.trac.wordpress.org/ticket/22342

test_22342();

function test_22342() {

	$post_id = 5; // Set this to some real post ID.

	update_post_meta( $post_id, '_test_22342', array( 'foo' => 'bar' ) );

	$meta_value = get_post_meta( 'post_id', '_test_22342', true );

	var_dump( $meta_value ); // bool(false)

	// Clean up.
	delete_post_meta( $post_id, '_test_22342' );
}

function filter_postmeta_22342( $check, $post_id, $meta_key, $single ) {

	if ( '_test_22342' == $meta_key )
		return array( 'foo' => 'test' );
}
add_filter( 'get_post_metadata', 'filter_postmeta_22342', 10, 4 );