If you attempt to power dust through a block via repeater, the dust remains unpowered UNLESS you put the dust down after powering the repeater. Conversely, if you have dust powered through a block by a repeater and unpower the repeater, the dust remains powered. Updating the redstone dust in either scenario activates/deactivates the dust to its proper state. This can be reproduced with the setups below, in a straight line or bent facing any direction, so long as the last step is powering/unpowering the repeater.