[PATCH] fetch: no FETCH_HEAD display if --no-write-fetch-head

[Jonathan Tan <jonathantanmy@xxxxxxxxxx>]

887952b8c6 ("fetch: optionally allow disabling FETCH_HEAD update",
2020-08-18) introduced the ability to disable writing to FETCH_HEAD
during fetch, but did not suppress the "<source> -> FETCH_HEAD" message
when this ability is used. This message is misleading in this case,
because FETCH_HEAD is not written. Also, because "fetch" is used to
lazy-fetch missing objects in a partial clone, this significantly
clutters up the output in that case since the objects to be fetched are
potentially numerous. Therefore, suppress this message when
--no-write-fetch-head is passed.

Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx>
---
This is on origin/jt/lazy-fetch.

This might be important for Stolee's maintenance prefetch patch [1] too
- presumably we don't want to show FETCH_HEAD there, as it would be
misleading and would clutter in the same way (albeit to a lesser
extent).

[1] https://lore.kernel.org/git/da64c51a8182ec13aeed8f0157079fb29a09ee85.1598380599.git.gitgitgadget@xxxxxxxxx/
---
 builtin/fetch.c          | 3 ++-
 t/t0410-partial-clone.sh | 7 +++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 320ba9471d..442df05f5a 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1023,11 +1023,12 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 				rc |= update_local_ref(ref, what, rm, &note,
 						       summary_width);
 				free(ref);
-			} else
+			} else if (write_fetch_head) {
 				format_display(&note, '*',
 					       *kind ? kind : "branch", NULL,
 					       *what ? what : "HEAD",
 					       "FETCH_HEAD", summary_width);
+			}
 			if (note.len) {
 				if (verbosity >= 0 && !shown_url) {
 					fprintf(stderr, _("From %.*s\n"),
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index d681e90640..584a039b85 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -183,7 +183,7 @@ test_expect_success 'missing CLI object, but promised, passes fsck' '
 '
 
 test_expect_success 'fetching of missing objects' '
-	rm -rf repo &&
+	rm -rf repo err &&
 	test_create_repo server &&
 	test_commit -C server foo &&
 	git -C server repack -a -d --write-bitmap-index &&
@@ -194,7 +194,10 @@ test_expect_success 'fetching of missing objects' '
 
 	git -C repo config core.repositoryformatversion 1 &&
 	git -C repo config extensions.partialclone "origin" &&
-	git -C repo cat-file -p "$HASH" &&
+	git -C repo cat-file -p "$HASH" 2>err &&
+
+	# Ensure that no spurious FETCH_HEAD messages are written
+	! grep FETCH_HEAD err &&
 
 	# Ensure that the .promisor file is written, and check that its
 	# associated packfile contains the object
-- 
2.28.0.402.g5ffc5be6b7-goog