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>

builtin/fetch-pack.c

@@ -858,19 +858,6 @@ static struct ref *do_fetch_pack(int fd[2],
 	return ref;
 }
 
-static int remove_duplicates(struct string_list *sought)
-{
-	int src, dst;
-
-	if (!sought->nr)
-		return 0;
-
-	for (src = dst = 1; src < sought->nr; src++)
-		if (strcmp(sought->items[src].string, sought->items[dst-1].string))
-			sought->items[dst++] = sought->items[src];
-	return dst;
-}
-
 static int fetch_pack_config(const char *var, const char *value, void *cb)
 {
 	if (strcmp(var, "fetch.unpacklimit") == 0) {
@@ -1090,7 +1077,7 @@ struct ref *fetch_pack(struct fetch_pack_args *my_args,
 
 	if (sought->nr) {
 		sort_string_list(sought);
-		remove_duplicates(sought);
+		string_list_remove_duplicates(sought, 0);
 	}
 
 	if (!ref) {

t/t5500-fetch-pack.sh

@@ -391,7 +391,7 @@ test_expect_success 'fetch mixed refs from cmdline and stdin' '
 test_expect_success 'test duplicate refs from stdin' '
 	(
 	cd client &&
-	test_must_fail git fetch-pack --stdin --no-progress .. <../input.dup
+	git fetch-pack --stdin --no-progress .. <../input.dup
 	) >output &&
 	cut -d " " -f 2 <output | sort >actual &&
 	test_cmp expect actual