Move "get_ack()" back to fetch-pack

In 41cb748 Linus moved this function to connect.c for reuse inside
of the git-clone-pack command.  That was 2005, but in 2006 Junio
retired git-clone-pack in commit efc7fa5.  Since then the only
caller has been fetch-pack.  Since this ACK/NAK exchange is only
used by the fetch-pack/upload-pack protocol we should move it back
to be a private detail of fetch-pack.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fetch-pack.c

@@ -157,6 +157,27 @@ static const unsigned char *get_rev(void)
 	return commit->object.sha1;
 }
 
+static int get_ack(int fd, unsigned char *result_sha1)
+{
+	static char line[1000];
+	int len = packet_read_line(fd, line, sizeof(line));
+
+	if (!len)
+		die("git fetch-pack: expected ACK/NAK, got EOF");
+	if (line[len-1] == '\n')
+		line[--len] = 0;
+	if (!strcmp(line, "NAK"))
+		return 0;
+	if (!prefixcmp(line, "ACK ")) {
+		if (!get_sha1_hex(line+4, result_sha1)) {
+			if (strstr(line+45, "continue"))
+				return 2;
+			return 1;
+		}
+	}
+	die("git fetch_pack: expected ACK/NAK, got '%s'", line);
+}
+
 static int find_common(int fd[2], unsigned char *result_sha1,
 		       struct ref *refs)
 {

cache.h

@@ -856,7 +856,6 @@ extern struct ref *find_ref_by_name(const struct ref *list, const char *name);
 extern struct child_process *git_connect(int fd[2], const char *url, const char *prog, int flags);
 extern int finish_connect(struct child_process *conn);
 extern int path_match(const char *path, int nr, char **match);
-extern int get_ack(int fd, unsigned char *result_sha1);
 struct extra_have_objects {
 	int nr, alloc;
 	unsigned char (*array)[20];

connect.c

@@ -107,27 +107,6 @@ int server_supports(const char *feature)
 		strstr(server_capabilities, feature) != NULL;
 }
 
-int get_ack(int fd, unsigned char *result_sha1)
-{
-	static char line[1000];
-	int len = packet_read_line(fd, line, sizeof(line));
-
-	if (!len)
-		die("git fetch-pack: expected ACK/NAK, got EOF");
-	if (line[len-1] == '\n')
-		line[--len] = 0;
-	if (!strcmp(line, "NAK"))
-		return 0;
-	if (!prefixcmp(line, "ACK ")) {
-		if (!get_sha1_hex(line+4, result_sha1)) {
-			if (strstr(line+45, "continue"))
-				return 2;
-			return 1;
-		}
-	}
-	die("git fetch_pack: expected ACK/NAK, got '%s'", line);
-}
-
 int path_match(const char *path, int nr, char **match)
 {
 	int i;