Jumping on farmland doesn't turn it into a dirt block

^{Update by [Mojang] Mega_Spud (Jay Wells):}
Summary:
Tilled soil / farmland cannot be damaged / trampled by players, only by animals.

Steps to Reproduce:

1. Jump or drop down onto farmland

Observed Results:
The farmland remains unchanged, and crops do not get displaced.

Expected Results:
The farmland should get trampled, reverting it to dirt, and displacing any planted crops.

Screenshots/Videos attached: Yes

Notes:

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Original Description:
Jumping on farmland won't do anything, it won't even drop the crops. This was working correctly before 1.2.0.18.
Here is a short video which shows how to reproduce this bug in version 1.2.0.22 on Windows 10.
https://youtu.be/Kj0Nx2dX1xg