[PATCHv2 2/2] sha1_file: fix iterating loose alternate objects

The string in 'base' contains a path suffix to a specific object; when
its value is used, the suffix must either be filled (as in
stat_sha1_file, open_sha1_file, check_and_freshen_nonlocal) or cleared
(as in prepare_packed_git) to avoid junk at the end.  loose_from_alt_odb
(introduced in 660c889e46d185dc98ba78963528826728b0a55d) did neither and
treated 'base' as a complete path to the "base" object directory,
instead of a pointer to the "base" of the full path string.

The trailing path after 'base' is still initialized to NUL, hiding the
bug in some common cases.  Additionally the descendent
for_each_file_in_obj_subdir function swallows ENOENT, so an error only
shows if the alternate's path was last filled with a valid object
(where statting /path/to/existing/00/0bjectfile/00 fails).

Signed-off-by: Jonathon Mah <redacted>
---
 sha1_file.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/sha1_file.c b/sha1_file.c
index 30995e6..fcb1c4b 100644
--- a/sha1_file.c
+++ b/sha1_file.c

@@ -3396,9 +3396,13 @@ static int loose_from_alt_odb(struct alternate_object_database *alt,
 			      void *vdata)
 {
 	struct loose_alt_odb_data *data = vdata;
-	return for_each_loose_file_in_objdir(alt->base,
-					     data->cb, NULL, NULL,
-					     data->data);
+	int r;
+	alt->name[-1] = 0;
+	r = for_each_loose_file_in_objdir(alt->base,
+					  data->cb, NULL, NULL,
+					  data->data);
+	alt->name[-1] = '/';
+	return r;
 }
 
 int for_each_loose_object(each_loose_object_fn cb, void *data)

-- 
2.3.0.rc2.2.g184f7a0