[15:36] <Bluefoxicy> holy crap, cp -af is non-deterministic
[15:36] <Bluefoxicy> cp -af foo/. bar/.
[15:37] <Bluefoxicy> if bar/qux/ is owned by your user and is r--r--r--, the FIRST run will try to copy foo/qux/baz.txt and FAIL.
[15:37] <Bluefoxicy> at that point, bar/qux/ has moved from (sorry, my fault) r-xr-xr-x to rwxr-xr-x
[15:38] <Bluefoxicy> yes, that's right:  cp -af changes the permissions on the directory, then fails.
[15:38] <Bluefoxicy> If you run the same command again, it will succed to make the replacement.
[15:39] <Bluefoxicy> english
[15:39] <Bluefoxicy> whatever.  You know what I'm talking about