fetch_pack(): update sought->nr to reflect number of unique entries
fetch_pack() removes duplicates from the "sought" list, thereby
shrinking the list. But previously, the caller was not informed about
the shrinkage. This would cause a spurious error message to be
emitted by cmd_fetch_pack() if "git fetch-pack" is called with
duplicate refnames.
Instead, remove duplicates using string_list_remove_duplicates(),
which adjusts sought->nr to reflect the new length of the list.
The last test of t5500 inexplicably *required* "git fetch-pack" to
fail when fetching a list of references that contains duplicates;
i.e., it insisted on the buggy behavior. So change the test to expect
the correct behavior.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>