Function sanitize_kernel_label 

pub fn sanitize_kernel_label(raw: &str) -> String

Sanitise a kernel label (the producer-side identity emitted by cargo ktstr’s resolver) into a nextest-safe identifier of the shape kernel_[a-z0-9_]+.

Replaces every [^A-Za-z0-9] byte with _, lowercases, collapses runs of _, and prefixes with kernel_. Empty / pathologically- short input collapses to kernel_ alone, which the parser downstream still recognises as a valid suffix (the empty sanitized marker just won’t disambiguate two kernels — but the producer side guarantees non-empty labels, so the empty case is defensive only).

Example mappings:

• 6.14.2 → kernel_6_14_2
• 6.15-rc3 → kernel_6_15_rc3
• git_tj_sched_ext_for-next → kernel_git_tj_sched_ext_for_next
• path_linux_a3f2b1 → kernel_path_linux_a3f2b1