Implements hook_menu_breadcrumb_alter().
function user_menu_breadcrumb_alter(&$active_trail, $item) {
// Remove "My account" from the breadcrumb when $item is descendant-or-self
// of system path user/%.
if (isset($active_trail[1]['module']) && $active_trail[1]['module'] == 'system' && $active_trail[1]['link_path'] == 'user' && strpos($item['path'], 'user/%') === 0) {
array_splice($active_trail, 1, 1);
}
}