block config page incorrectly displays nodes for other blocks

With multiple headerimage blocks, when you visit the block configure page (ie /admin/block/configure/headerimage/2) the table that displays the nodes assigned to the current headerimage block, also shows nodes assigned to other headerimage blocks.

The fix is very simple: change the "AND" to a "WHERE" on line 638 in the headerimage_block_configure function. I've attached a patch file for you in case you want it.