This GNU test is a shared test for mv and cp that mainly checks the inter-partition copying of both utilities when a symlink is involved. mv is already fully compatible with this test case, but in the case of cp, the test is failing, not because of anything related to inter-partition copying but because of how uu-cp handles symlink destinations when --rem and --backup are given.

For example

echo xyz > loc_reg
mkdir innerdir
echo abc > innerdir/innerfile
ln -sr innerdir/innerfile innerdir/sl
cp --rem -b loc_reg innerdir/sl

this should give us

>> ls -l innerdir
total 8
-rw-r--r-- 1 mhead mhead 4 Jul 20 19:03 innerfile
-rw-r--r-- 1 mhead mhead 4 Jul 20 19:07 sl
lrwxrwxrwx 1 mhead mhead 9 Jul 20 19:03 sl~ -> innerfile

What cp did was back up the symlink, remove the symlink at the destination path, and then copy the source file to that path. However, in uu-cp's case, this would produce an error saying cp: No such file or directory (os error 2), and inside the innerdir, it would look like this:

» ls -l innerdir
total 4
-rw-r--r-- 1 mhead mhead 4 Jul 20 19:15 innerfile
lrwxrwxrwx 1 mhead mhead 9 Jul 20 19:15 sl~ -> innerfile

After backing up and removing the symlink, uu-cp failed to copy the source to the destination.