mv: create cross-device directory entries relative to the destination descriptor

DEVELOPMENT.md

@@ -1,4 +1,5 @@
 <!-- spell-checker:ignore (flags) Ccodegen Coverflow Cpanic Cinstrument Zpanic reimplementing toybox RUNTEST CARGOFLAGS nextest prereq autopoint gettext texinfo automake findutils shellenv libexec gnubin toolchains gsed -->
+<!-- spell-checker:ignore fakeroot setid -->
 
 # Setting up your local development environment
 
@@ -136,6 +137,15 @@ If you would prefer to test a select few utilities:
 cargo test --features "chmod mv tail" --no-default-features
 ```
 
+The Linux cross-device `mv` ownership regression additionally uses the optional
+`fakeroot` executable and requires a writable `/dev/shm`. Run it as a non-root
+user; it reports a skip when fakeroot is unavailable or `/dev/shm` is on the
+source filesystem:
+
+```shell
+cargo test --no-default-features --features mv test_mv_cross_device_fakeroot_ownership_and_setid
+```
+
 If you also want to test the core utilities:
 
 ```shell

src/uu/mv/Cargo.toml

@@ -42,7 +42,7 @@ windows-sys = { workspace = true, features = [
 ] }
 
 [target.'cfg(unix)'.dependencies]
-rustix = { workspace = true, features = ["fs"] }
+rustix = { workspace = true, features = ["fs", "process"] }
 
 [[bin]]
 name = "mv"