Merge branch 'jk/maint-pack-objects-compete-with-delete'

* jk/maint-pack-objects-compete-with-delete:
  downgrade "packfile cannot be accessed" errors to warnings
  pack-objects: protect against disappearing packs

builtin/pack-objects.c

@@ -804,6 +804,10 @@ static int add_object_entry(const unsigned char *sha1, enum object_type type,
 		off_t offset = find_pack_entry_one(sha1, p);
 		if (offset) {
 			if (!found_pack) {
+				if (!is_pack_valid(p)) {
+					warning("packfile %s cannot be accessed", p->pack_name);
+					continue;
+				}
 				found_offset = offset;
 				found_pack = p;
 			}

cache.h

@@ -1057,6 +1057,7 @@ extern struct packed_git *add_packed_git(const char *, int, int);
 extern const unsigned char *nth_packed_object_sha1(struct packed_git *, uint32_t);
 extern off_t nth_packed_object_offset(const struct packed_git *, uint32_t);
 extern off_t find_pack_entry_one(const unsigned char *, struct packed_git *);
+extern int is_pack_valid(struct packed_git *);
 extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsigned long *);
 extern unsigned long unpack_object_header_buffer(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
 extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);

sha1_file.c

@@ -1987,7 +1987,7 @@ off_t find_pack_entry_one(const unsigned char *sha1,
 	return 0;
 }
 
-static int is_pack_valid(struct packed_git *p)
+int is_pack_valid(struct packed_git *p)
 {
 	/* An already open pack is known to be valid. */
 	if (p->pack_fd != -1)
@@ -2038,7 +2038,7 @@ static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 			 * was loaded!
 			 */
 			if (!is_pack_valid(p)) {
-				error("packfile %s cannot be accessed", p->pack_name);
+				warning("packfile %s cannot be accessed", p->pack_name);
 				goto next;
 			}
 			e->offset = offset;