Some blocks cannot be placed facing a wall with /setblock or /fill + datavalues or block states

When using /setblock to place a dispenser with a rotation datavalue, if the front of the block is against a wall the dispenser will point the opposite direction when placed.

To Replicate: Place a block. Attempt to spawn a dispenser one block north of it, with a rotation data value of 3 (Telling the dispenser to "look" south). The block will instead face north. Same happens for east/west.

Affects the following blocks:

• dropper
• dispenser
• observer (can't see due to MC-108054, may be affected if that's fixed)
• (lit_)furnace

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Code analysis by Marcono1234 can be found in this comment.