Converting a world turns Monster Spawners into Pig Spawners

Cannot reproduce. Please attach seed and coordinates of an affected spawner.

This happened to me as well. I accidentally loaded my snapshot enabled world in 1.8.8. When I loaded it back up with the appropriate snapshot (15w51b) the skeleton spawner was a pig spawner.

Seed: 784643794644085780
Coords: (-201, 25, 602)

Hi,
This bug happend to me as well. started world in snapshot 15w51b
seed -740566427
coords 697 28 453
xyz 697 29 453

I think you both understood the report wrong. It says:

after converting a world from 1.8.8/1.8.9 to a 1.9 Snapshot

What you both are confirming is from 1.9 Snapshot to 1.8.8 / 1.8.9 which is invalid because downgrading is not supported.

Thank you for the fast repl, does that mean i have to start a new game? does that mean every spawner i find will be pig spawner?

No, if you open it in 1.9 again existing spawners stay pig spawners, but all new generated spawners should work correctly