Merge branch 'bw/cp-a-is-gnuism'

* bw/cp-a-is-gnuism:
tests: "cp -a" is a GNUism

diff --combined t/t5400-send-pack.sh
index 78ab17793894ed902468e1f7af5841b67eeef2ff,418f515ada50f1687a010a8f335f9363da5a0a3b..129fc88bd28e8ea85e81310aec860df808949447
--- 1/t/t5400-send-pack.sh
--- 2/t/t5400-send-pack.sh
+++ b/t/t5400-send-pack.sh
@@@ -159,7 -159,7 +159,7 @@@ test_expect_success 'receive-pack runs 
            git commit -a -m "Second commit" &&
            git repack
        ) &&
-       cp -a parent child &&
+       cp -R parent child &&
        (
            # Set the child to auto-pack if more than one pack exists
            cd child &&
@@@ -174,7 -174,8 +174,7 @@@
            cd parent &&
            echo "Even more text" >>file.txt &&
            git commit -a -m "Third commit" &&
 -          git send-pack ../child HEAD:refs/heads/test_auto_gc >output 2>&1 &&
 -          grep "Auto packing the repository for optimum performance." output
 +          git send-pack ../child HEAD:refs/heads/test_auto_gc
        ) &&
        test ! -e child/.git/objects/tmp_test_object
  '