lint message paths are absolute in some cases

[matthiaskrgr]

mkdir test
cd test
wget https://crates.io/api/v1/crates/crc/1.8.1/download
mv download crc-1.8.1.tar.gz
tar -xvf crc-1.8.1.tar.gz
cd crc-1.8.1
cargo clippy -- -Wclippy::pedantic

The crate seems to generate some code as part of its build.rs and that code is dumped somewhere into the target dir.
Now when we issue lint warnings about that code (that is inside the target dir), the path to the file is an absolute (canonicalized?) path and not a relative path from the crate root, as usual:

warning: long literal lacking separators
   --> /tmp/test/crc-1.8.1/target/debug/build/crc-a8ff9075a6d24ab1/out/crc64_constants.rs:509:5
    |
509 |     11317545863582056448,
    |     ^^^^^^^^^^^^^^^^^^^^ help: consider: `11_317_545_863_582_056_448`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unreadable_literal

Is that intentional?
Why is it not a relative path from the crate root like all the warnings (something like target/debug/build/crc-a8ff9075a6d24ab1/out/crc64_constants.rs:509:5)