The bug
Using a fire charge on a block of TNT primes it, but the fire charge is consumed, even if the player is in creative mode. Using it to set blocks on fire that aren't TNT does not consume the fire charge.
Linked issues
is duplicated by 7
2 more links
relates to 2
Attachments
Comments 9
Relates to MC-671
Not sure if that would be helpful, since it's 5 years apart, the reason in the code is likely not the same.
Affects 18w03b and therefore likely 18w03a