sparse-checkout: use improved unpack_trees porcelain messages

setup_unpack_trees_porcelain() provides much improved error/warning
messages; instead of a message that assumes that there is only one path
with a given problem despite being used by code that intentionally is
grouping and showing errors together, it uses a message designed to be
used with groups of paths.  For example, this transforms

    error: Entry '	folder1/a
	folder2/a
    ' not uptodate. Cannot update sparse checkout.

into

    error: Cannot update sparse checkout: the following entries are not up to date:
	folder1/a
	folder2/a

In the past the suboptimal messages were never actually triggered
because we would error out if the working directory wasn't clean before
we even called unpack_trees().  The previous commit changed that,
though, so let's use the better error messages.

Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index a55c60d759..aa81199f85 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -112,7 +112,9 @@ static int update_working_directory(struct pattern_list *pl)
 
 	repo_hold_locked_index(r, &lock_file, LOCK_DIE_ON_ERROR);
 
+	setup_unpack_trees_porcelain(&o, "sparse-checkout");
 	result = update_sparsity(&o);
+	clear_unpack_trees_porcelain(&o);
 
 	if (result == UPDATE_SPARSITY_WARNINGS)
 		/*