All rail types can be supported by trapdoors even when the trapdoor is open. This used to affect redstone repeaters, wire, and comparaters, but no longer does.

Steps to Reproduce:

1. Place a trap door down in the 'open=false' and 'half=top' blockstate
2. Place down one of the affected blocks in the "Notes" section on top of the trapdoor
3. Open the trapdoor with your hand, or redstone

Observed Results:

The block will not break, but instead float above the (mostly) empty supporting block.

Expected Results:

The block would break as there is no block beneath it to support it properly.

Screenshots/Videos:

2023-10-15_19-47-07.mp4

Notes:

1. Related to other supporting block issues:
   MC-92758 MC-264563 MC-148202 MC-222212 MC-213638
2. Standing signs and banners were added to this issue, but later removed, as they were not part of the original issue, and have unique placement behavior unrelated to rails (the last affected block).

Original Description:

^{(The original description of the issue when it was triaged, by Coder01)}

When a trapdoor is in the flat form (Closed) it is possible to place rails on them. This would be fine except that you can then open the trapdoor and still have the rail on top of it. This is a fully functional rail, however when the block is updated by anything other than the rail, it pops off as it should directly after the trapdoor is opened. Attached is a video showing everything I have described.

This also applies to e.g. redstone dust and repeaters. Other blocks like torches do pop off though