Your provided command does not work in a command block, and only works from chat because whitespace is trimmed out: MC-65034
I just double checked this and you are indeed correct. Turns out the mcedit-filter to import Command Block commands from textfiles that I was using before also trims whitespace.
However, I still consider the current behaviour a bug considering almost every single compiler and interpreter out there doesn't care about extra spaces and tab stops (and neither do any minecraft data files) in order to make writing and reading code not painful. 🙂
Observer blocks create 2 tick (gameticks) pulses now. Comparators aren't powered by 2 tick pulses in general, ergo this is not a bug.
Is this still an issue in the latest snapshot 16w44a? If so please update the affected versions.
Updated it. Again, (in singleplayer) this happens in any version since the 1.3.1 SSP/SMP merge.
Sound related to MC-12363
I guess it is a similar sort of desync as the end result is identical (wrong client-side inventory), and I can see an additional "update your inventory, client!"-message after the client failed to perform an action "band-aid-fixing" both issues.
But this report is about specific instances where the server thinks you couldn't place a block because you tried to place it inside your character model even though that can clearly not be the case, which is something that shouldn't happen in the first place, even if the band-aid-fix still makes sense. 😉
Effect levels above level 4 aren't officially supported. (Not supported as in if they cause issues, it is your problem and not something Mojang will fix.)
This is an issue present in all versions that use generic.followRange.
Considering spawning 20 Zombies with a 160 block follow range in version 1.8.9 creates no noticeable lag whatsoever whereas spawning only one in 16w02a makes the game basically unplayable, I find that very hard to believe.
Considering everything else that is exposed to end users in the game is translatable I'm pretty sure this fulfills any definition of a programming oversight which is what bugs are.