Water/lava bucket can be used to destroy ladders

Confirmed.

Bug or Feature ?

Either it shouldn't be possible to replace a ladder with water or it should drop a ladder, see MC-3737.

Have seen this behaviour long since 1.4.2 and have just confirmed this in 1.4.6 SSP. This happens in 1x1 laddershafts of any height when you apply a water bucket on any unoccupied wall of the shaft (not just only the opposite one). This also happens with other wall-mounted items like torches. This behaviour also applies to lava buckets as well (due to same mechanics i suppose).

Lava bucket proof and torch destruction proof

Torch destruction is intentional, but not ladder destruction.

According to MC-72614 this is back in 1.8. (It does drop items though.)
EDIT: This affects all non-solid blocks (except for replacing water and lava with the opposite liquid) and could be merged with MC-33015.

EDIT 2: Also affects 1.8.1-pre1.

Still in 1.8.1-pre2.

Confirmed for 15w46a

Relates to MC-84963.

Changing the reporter to myself as the original reporter is no longer active.

Confirmed for 1.12.2 and 17w43b.