The bug

Trying to replace a replaceable block, such as Tall Grass, Ferns, a Snow layer, Vines etc, with specific blocks isn't possible, if you try placing one of those blocks on the side of the block you want to replace.

Only attempting to place at sides of replaceable blocks makes this happen.

The "specific blocks" are Banners, Signs, Doors, Beds, Levers¹, Buttons¹ and Double Plants²

_{¹ Bug reproduction only when no other same-height blocks are next to the replaceable block.
² Bug reproduction only when trying to place at side-hitbox of Double Tallgrass and Large Fern blocks.}

Note: In version 1.8.8, you can't replace replaceable blocks with the specific blocks by placing them on the hitbox-top of the replaceable blocks. This isn't the case with 15w46a and all other tested snapshots. The fix of MC-64139 may have made it this way.

Video

https://youtu.be/Sh9r_fb6GN0 (Uploaded by Crazy_Matt)

_{Original reporter: Crazy_Matt}