Breaking bd not dropping side block

So i was playing survival and wanted to replace my with another colored bed.

the old bed had an sign attached to the side. when i broke the bottom half of the bed i got the bed but not the sign.

Expected Behaviour:

 I should have gotten the bed and the sign as n item back.

Actual Behaviour:

I only got the Bed as the item.

How to reproduce:

a bed with a sign attacked on 1 of the sides and breaking the other half of the bed with no sign.