I have a diskless machine with root mounted via NFS (4). Emerge works just fine but at the end of compilation it cannot remove /var/tmp/portage/*/*/temp directory since it is not empty. Most likely there is still a (parallel) process accessing a file in that directory and rm cannot delet it.
This is not a support forum. Setting up NFS share permissions problem is a local affair and not a Gentoo bug.
Too fast... I have the right permissions. Searching more I could find https://bugs.gentoo.org/show_bug.cgi?id=364143 So rather put it as duplicate then just close it. Nice that I can do it myself. *** This bug has been marked as a duplicate of bug 364143 ***