fetch-pack: fix object_id of exact sha1

Commit 58f2ed0 (remote-curl: pass ref SHA-1 to fetch-pack as well,
2013-12-05) added support for specifying a SHA-1 as well as a ref name.
Add support for specifying just a SHA-1 and set the ref name to the same
value in this case.

Signed-off-by: Gabriel Souza Franco <gabrielfrancosouza@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fetch-pack.c

@@ -16,10 +16,20 @@ static void add_sought_entry(struct ref ***sought, int *nr, int *alloc,
 	struct ref *ref;
 	struct object_id oid;
 
-	if (!get_oid_hex(name, &oid) && name[GIT_SHA1_HEXSZ] == ' ')
-		name += GIT_SHA1_HEXSZ + 1;
-	else
+	if (!get_oid_hex(name, &oid)) {
+		if (name[GIT_SHA1_HEXSZ] == ' ') {
+			/* <sha1> <ref>, find refname */
+			name += GIT_SHA1_HEXSZ + 1;
+		} else if (name[GIT_SHA1_HEXSZ] == '\0') {
+			; /* <sha1>, leave sha1 as name */
+		} else {
+			/* <ref>, clear cruft from oid */
+			oidclr(&oid);
+		}
+	} else {
+		/* <ref>, clear cruft from get_oid_hex */
 		oidclr(&oid);
+	}
 
 	ref = alloc_ref(name);
 	oidcpy(&ref->old_oid, &oid);

t/t5500-fetch-pack.sh

@@ -531,6 +531,20 @@ test_expect_success 'shallow fetch with tags does not break the repository' '
 		git fsck
 	)
 '
+
+test_expect_success 'fetch-pack can fetch a raw sha1' '
+	git init hidden &&
+	(
+		cd hidden &&
+		test_commit 1 &&
+		test_commit 2 &&
+		git update-ref refs/hidden/one HEAD^ &&
+		git config transfer.hiderefs refs/hidden &&
+		git config uploadpack.allowtipsha1inwant true
+	) &&
+	git fetch-pack hidden $(git -C hidden rev-parse refs/hidden/one)
+'
+
 check_prot_path () {
 	cat >expected <<-EOF &&
 	Diag: url=$1