bug#15738: Inconsistency & bug cp -a A B doesn't reliably create 'B' as a copy of 'A' even w/--remove-destination

[Linda Walsh]

with "--remove-destination", I think this a bug.  W/o it, it is
inconsistent with the requirement not to use "dirname/." to refer to
contents in 'rm'.

details:
        mkdir a
        touch a/file
        mkdir a/dir
        cp -a a b       #'ok'
        touch a/file2

now:
        cp -au a b      
(or)
        cp -a a b

Either form creates another complete copy of 'a' in directory 'b'.
(Note, this is historical behavior).

FWIW,
     cp -a a/ b/
behaves the same way.

However,
        cp -a a/. b/.
fails the 1st time, but not if 'b' is already created (by using a form
from above).

Technically, though, the above should fail, as it says
says to copy the dir-entry for '.' over the dot entry
in 'b'.

While using '.' as a shorthand for contents of a dir has been
normal, it no longer works in utils like 'rm'.

---!!!---

*More troublesome* is that:

        cp -a --remove-destination a b

doesn't work, but duplicates the behaviors of the above.

If 'b' is removed *before* the copy, as is documented,
then it should be no different than the case where 'a' is
copied to a non-existent 'b'.