The bug

Upon killing an enderman holding a block of powder snow (minecraft:powder_snow), the enderman drops a powder snow bucket (as well as ender pearls occasionally, as normal). The expected behaviour is for the enderman to only drop ender pearls, because the actual block of powder snow does not include the bucket.

Removing the powder snow bucket drop would make this consistent with other held blocks like water and lava. When an enderman is killed holding one of these blocks, the bucket is not dropped.

If endermen can pick up powder snow in later snapshots, this would be a way to duplicate buckets. Currently, however, this is only accessible through commands.

How to reproduce

1. Obtain an enderman holding powder snow by running the command:

   /summon minecraft:enderman ~ ~ ~ {NoAI:1b,carriedBlockState:{Name:"minecraft:powder_snow"}} 

2. Kill the enderman
     Notice how a powder snow bucket is dropped