Formatter inserts trailing newline at the end of a file even when inside a `fmt: off` region

[MilkClouds]

Summary

title is all.

you can test this bug with:

# fmt: off
print(1,2,3,4,5,9,13518,8315987831959831,3851758979515,31958139573175915,158315897151935,135815798151,)

make sure end of file does not contain newline. run ruff format. then newline is inserted.

Version

ruff 0.12.4

[ntBre]

I can reproduce this:

$ printf '# fmt: off\n1' | ruff format --diff -
@@ -1,2 +1,2 @@
 # fmt: off
-1
\ No newline at end of file
+1

It's not strictly related to W292, which is a lint rule and shouldn't be affected by the formatter, but the formatter does add a newline to the end of the file even with # fmt: off.