If mooshroom that is attached to a fence via a lead is sheared the lead dissapears

Steps to reproduce the bug:

• Use lead to attach the mooshroom cow to a fence
• Shear the mooshroom cow

Result:

• Lead visualy appears to be still attached to the fence
• Cow is not attached to the lead and can move freely
• When clicked the lead on the fence no item is dropped

Expected Result
The lead would remain and not dissapear