The Bug
In the latest snapshot, using a /setblock or /fill command to place a directional block with blockdata specifying direction, it will place the block with the block's default direction.
Steps to reproduce
Block  | Command  | 
|---|---|
tripwire  | 
  | 
redstone_wire  | 
  | 
fence  | 
  | 
glass_pane  | 
  | 
stained_glass_pane  | 
  | 
iron_bars  | 
  | 
Affected blocks
Note: This list might differ from the one in MC-109591.
redstone_wire(directions)
glass_pane (directions)
stained_glass_pane (directions)
iron_bars (directions)
all fences (directions)
fire (directions)
tripwire (directions)
all stairs (shape)
cobblestone_wall (directions and up/pillar)
grass/dirt/mycelium (snowy)
fence_gate (in_wall)
powered_repeater (locked)
flower_pot (contents)
Updated with step to reproduce with fences (thanks Neko!)