Running them twice usually destroyed the target binary. E.g., the
second `make objlink' in `make objlink; make; make objlink' replaced
the `cat' binary by a symlink cat@ -> /usr/obj/usr/src/bin/cat.
`ln -fs' is unusable when the target might be a symlink that resolves
to a directory. Then -f applies to a file in the directory and not
to the symlink. This seems to be the standard (and sometimes useful)
behaviour.
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