Needed a quick drop in script for functions.php to add SKU field on the general tab within WooCommerce product editor

WooCommerce-Edit-General-SKU.php

<?php

// add sku on woocommerce product editor >> general tab
add_action( 'woocommerce_product_options_general_product_data', 'add_the_sku_to_general_product_field' );
function add_the_sku_to_general_product_field() {
    global $post;
    $product_sku = get_post_meta( $post->ID, '_sku', true );
?>
<div class="options_group">
<p class="form-field _sku_field ">
	<label for="_sku">
		<abbr title="Stock Keeping Unit">SKU</abbr>
	</label>
	<!--<span class="woocommerce-help-tip"></span>-->
	<input type="text" class="short" style="" name="_sku" id="_sku_alias" value="<?php echo $product_sku; ?>" placeholder=""
		   onchange="(function(){
					jQuery('input#_sku').val(jQuery('input#_sku_alias').val());
			})();" >
</p>
</div>
<?php
}