clone: remove fetch_if_missing=0

Commit 6462d5eb9a ("fetch: remove fetch_if_missing=0", 2019-11-08)
strove to remove the need for fetch_if_missing=0 from the fetching
mechanism, so it is plausible to attempt removing fetch_if_missing=0
from clone as well. But doing so reveals a bug - when the server does
not send an object directly pointed to by a ref, this should be an
error, not a trigger for a lazy fetch. (This case in the fetching
mechanism was covered by a test using "git clone", not "git fetch",
which is why the aforementioned commit didn't uncover the bug.)

The bug can be fixed by suppressing lazy-fetching during the
connectivity check. Fix this bug, and remove fetch_if_missing from
clone.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -927,8 +927,6 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 	struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
 
-	fetch_if_missing = 0;
-
 	packet_trace_identity("clone");
 	argc = parse_options(argc, argv, prefix, builtin_clone_options,
 			     builtin_clone_usage, 0);
@@ -1265,7 +1263,6 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	}
 
 	junk_mode = JUNK_LEAVE_REPO;
-	fetch_if_missing = 1;
 	err = checkout(submodule_progress);
 
 	strbuf_release(&reflog_msg);

connected.c

@@ -62,7 +62,8 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 		 * received the objects pointed to by each wanted ref.
 		 */
 		do {
-			if (!repo_has_object_file(the_repository, &oid))
+			if (!repo_has_object_file_with_flags(the_repository, &oid,
+							     OBJECT_INFO_SKIP_FETCH_OBJECT))
 				return 1;
 		} while (!fn(cb_data, &oid));
 		return 0;