After some short tests we found strip failing for any regular user as well inside fakeroot on files with permission 444 or 555:
$ cp /lib/libacl.so.1 /tmp/testlib.so; chmod 444 /tmp/testlib.so; /usr/bin/strip /tmp/testlib.so /usr/bin/strip: unable to copy file '/tmp/testlib.so'; reason: Permission denied Dan could confirm this on his system.
