connected.c: free the "struct packed_git"

connected.c: free the "struct packed_git"

The "new_pack" we allocate in check_connected() wasn't being
free'd. Let's do that before we return from the function. This has
leaked ever since "new_pack" was added to this function in
c6807a40dcd (clone: open a shortcut for connectivity check,
2013-05-26).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>