So After other Players and people have done testing a HUGE map making bug has accured in 1.9 and 1.9.2

Changing the Nether Dimensions Biome to Tiaga, Desert, or End and then Changing the END Dimensions Biome to Nether and Killing the Ender Dragon after world will Reset ONLY The Nether Dimensions Entire Map.

Regardless that renaming a Dimensions Biomes isn't in default MC this was never a bug before 1.9+

THIS BUG CAN occur even if the Nether AND End are NOT Touched at all with any editing software JUST Building in the Nether, and then killing the dragon has a chance to reset the Nether and Lose all things built there.

this is a Shame and evidence from this happening is here:

https://www.twitch.tv/craft_kid/v/58550485

^this highlight above is a Snipit of a 13 Hour Live Stream i did Straight of Building a Custom Map for a 1.9 Server ; -; and they wanted an ICE Nether and Netherack End dimension Revamp D: ^

in the stream highlight above at: 1:51:11 is where i finally was pretty much completed the Nether Revamp.

and i figured id start on the End Dimension Revamp Here:
02:24:35

and this is where afterward killed the dragon: 2:39:40

this is where i was going to show one of my viewers the ice nether i was so proud of custom hand making ; -; : 3:26:40

i was really shocked that this glitch would happen its a large risk for people who like to make custom minecraft maps that are custom world maps: {EI: Nether, End, Over world Revamps] > all in 1 map custom made :L

im going to try and redo the ice nether again later today or so with more backups so i dont lose 4 hours every time but this should get fixed right away as its a potential risk for all map makers.

sorry for my spelling and punctuation, i am dyslexic and have trouble with spelling and punctuation.

full stream over view of begining of working on the map is located here incase more indepth proof or review of my steps to see why this happened:

https://www.twitch.tv/craft_kid/v/58326549

i really hope this can get resolved for 1.10 in a couple of months :L