Summary should explain everything, if not look at the screenshots.
Code analysis by @unknown can be found in this comment.
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Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Note: this is a automatic message, so apologies if I miss something.

Is this still a concern in the current Minecraft version 1.7.4 / Launcher version 1.3.8 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Confirmed for
14w31a because MC-64700 describes this bug in 14w31a
Minecraft 1.8-pre 1
confirmed for 1.8.2 pre1
Probably related to MC-75426.

Confirmed for
15w51b
Affects cake as well, see TIL: Cakes give off a redstone signal when using comparators
Confirmed for 1.9.3 pre-3

Please link to this comment in the description
The following is based on a decompiled version of Minecraft 1.9 using MCP 9.24 beta.
The reason for this is that the classes net.minecraft.block.BlockCauldron
and net.minecraft.block.BlockCake
do not override the method net.minecraft.block.Block.breakBlock(World, BlockPos, IBlockState)
to call the method net.minecraft.world.World.updateComparatorOutputLevel(BlockPos, Block)
.
Confirmed for 1.9.4
Confirmed for 16w20a
Is this still an issue on the latest snapshot 16w44a?
Yes

@unknown, you, as the reporter of the bug, can add the affected version yourself
Confirmed for 17w13b
Can confirm for release 1.12
Merged into MC-120986.
Confirmed.