They weren't talking about redstone lamps being powered by adjacent copper bulbs but rather redstone dust loses its power when the power is traveling down a copper bulb.
(Edit): look at the photo submitted it clearly shows what I said. This is a issue that needs to be fixed.
Yes, the server is vanilla. It is on linux so I usually just use Ctrl+C or maybe it's Ctrl+X, I forget. I just logged in to restore a backup and notice it happened again. After stopping minecraft I noticed still 50% with only a small drop. I believe that maybe linux cache or linux buffer for the disk is getting filled up and not emptying. I will update this page if I find a solution. It is strange because centos is also stock with no extra software except java and minecraft.
Well, the problem I reported MC-11901 was said to be a duplicate of this problem. However, before updating I did not have the problem. I guess the bug I reported is not a duplicate then but it does seem very similar.
Many of my contraptions are broken after updating to 1.5 from 1.4.7. I hope they change this soon. :C
This is still a current issue