When a repeater is placed in direction f=0 facing a torch it flashes on for 1 redstone tick this does not occur in any other direction. I have videoed it at http://youtu.be/Z6NEc4_Eh8o
Linked issues
is duplicated by 8
MC-5712
Light sensor bug with repeaters on north side
Resolved
MC-5714
Repeater flashes when pointing forward
Resolved
MC-5724
Redstone repeater flickering when placed near redstone
Resolved
MC-5863
Repeaters placed on the Northern side of a Redstone block will be powered for a single tick.
Resolved
MC-6210
Redstone repeater pulses when placed perpendicular to a redstone current
Resolved
3 more links
Pretty old bug, the repeater does not have to be facing a redstone torch either, it can be beside it, also, please remove environment info as this applies to any environment.