clone,fetch: catch non positive --depth option value

Instead of simply ignoring the value passed to --depth option when
it is zero or negative, catch and report it as an error to let
people know that they were using the option incorrectly.
Original-patch-by: NAndrés G. Aragoneses <knocte@gmail.com>
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -797,6 +797,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	if (option_local > 0 && !is_local)
 		warning(_("--local is ignored"));
 
+	/* no need to be strict, transport_set_option() will validate it again */
+	if (option_depth && atoi(option_depth) < 1)
+		die(_("depth %s is not a positive number"), option_depth);
+
 	if (argc == 2)
 		dir = xstrdup(argv[1]);
 	else

builtin/fetch.c

@@ -1045,6 +1045,10 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	/* no need to be strict, transport_set_option() will validate it again */
+	if (depth && atoi(depth) < 1)
+		die(_("depth %s is not a positive number"), depth);
+
 	if (recurse_submodules != RECURSE_SUBMODULES_OFF) {
 		if (recurse_submodules_default) {
 			int arg = parse_fetch_recurse_submodules_arg("--recurse-submodules-default", recurse_submodules_default);