Soul speed effect carrys on when shifting on the edge of blocks that aren't soul soil or soul sand

Put the summary of the bug you're having here

What I expected to happen was...:
when I shift off of soul soil with soul speed It should stop the effect

What actually happened was...:
speed carried on

Steps to Reproduce:
1. wear soul speed boots
2. shift walk onto block (on the outside) that isn't a soul block 
3. carries on forever