If I understand the wiki correctly, powered redstone dust is only supposed to power blocks and mechanisms it is pointing at. However opaque blocks adjacent to the dust, which the dust does not point at, are also powered.
See the screenshots. The torch should not turn off when the lever is turned on, as the dust only points to the mechanism (sticky piston) near it.
Let me know if I misunderstand how this is supposed to work.
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That is a known bug which has already been reported as MCPE-16892. Next time please search for existing tickets (but since there are so many redstone direction bugs it isn't really easy to search though...)