apt-add-repository incorrectly forces lowercase

[Malcolm Scott]

I have a local APT repository with a non-lowercase suite identifier. apt-add-repository always forces it into lowercase, which causes apt to emit warnings when it notices the mismatch:

$ sudo apt-add-repository "deb http://example.com/deb FooBar Baz"
Repository: 'deb http://example.com/ foobar Baz'
Description:
Archive for codename: foobar components: Baz
More info: http://example.com/
Adding repository.
Press [ENTER] to continue or Ctrl-c to cancel.
(...)
$ sudo apt update
(...)
W: Conflicting distribution: http://example.com/deb foobar InRelease (expected foobar but got FooBar)

[Jeremy Bícha (jbicha)]

Could you use a lower case suite in your local apt repository as a workaround for this issue?

I feel like it's a bit of a standard to have lowercase: jammy, bookworm, virginia etc.