When redstone is placed next to another piece, it normally makes a line. But in Minecraft 14w17a-14w25a, instead of -----, (dashes as redstone), it looks like | | | |. it's turned.
Sorry, no screenshot. My Mac has some problems. just make a straight redstone wire. that will replicate the glitch.
migrated
This issue does not happen with the standard vanilla client. You are using a resource pack that has not been updated.