This is a huge bug, but I have not tested this in 1.4 yet. The issue is that there are directional issues with minecarts, redstone, etc. that include directional block placement. For example, when making a minecart station of sorts, sometimes, the rails do not position in logical order, bugging out the minecart on the track.
I believe that the bug is caused because the blocks are programmed to a specific direction, and bugs out when it isn't facing that specific direction.
Linked issues
duplicates 1
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I have tested this in 1.4 now, it appears that some pulses of redstone differ for different directions (Using a t-flip flop with the new redstone repeater locks.) There are 2 pulses, 1 main pulse, and 1 short pulse which comes right after the main pulse (The bug). But this did not happen when I faced east.
I think you lied in one of these...
Also you should show concrete examples (with screenshots) of this bug. "minecart station of sorts" is not enough.