Get a one-block tall wall and place two rails connected slantedly. Better powered "Powered Rail". Place a block above the slanted one in which situation this will cut the connection of Redstone. The two rails will not be cut. Run a minecart from the lower rail and see it go through the obstuction.
See MC-42414.
Related issues
is duplicated by
Attachments
Comments

[media]

Hmm... is the same on the PC version, i think Jeb or Notch confirmed that they will not fix it...

Confirmed in Creative mode for Minecraft PE 0.9.4
Edit: Updated to 0.9.5

It works like on pc, sadly.