/usr/share/doc/libstd-rust-dev/changelog.Debian.gz is in libstd-rust-dev 1.24.1+dfsg1+llvm-0ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libstd-rust-dev/../libstd-rust-1.24/changelog.Debian.gz