builtin/repack.c: extract has_existing_non_kept_packs()

When there is:

  - at least one pre-existing packfile (which is not marked as kept),
  - repacking with the `-d` flag, and
  - not doing a cruft repack

, then we pass a handful of additional options to the inner
`pack-objects` process, like `--unpack-unreachable`,
`--keep-unreachable`, and `--pack-loose-unreachable`, in addition to
marking any packs we just wrote for promisor remotes as kept in-core
(with `--keep-pack`, as opposed to the presence of a ".keep" file on
disk).

Because we store both cruft and non-cruft packs together in the same
`existing.non_kept_packs` list, it suffices to check its `nr` member to
see if it is zero or not.

But a following change will store cruft- and non-cruft packs separately,
meaning this check would break as a result. Prepare for this by
extracting this part of the check into a new helper function called
`has_existing_non_kept_packs()`.

This patch does not introduce any functional changes, but prepares us to
make a more isolated change in a subsequent patch.

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

builtin/repack.c

@@ -105,6 +105,11 @@ struct existing_packs {
 	.non_kept_packs = STRING_LIST_INIT_DUP, \
 }
 
+static int has_existing_non_kept_packs(const struct existing_packs *existing)
+{
+	return existing->non_kept_packs.nr;
+}
+
 static void mark_packs_for_deletion_1(struct string_list *names,
 				      struct string_list *list)
 {
@@ -1048,7 +1053,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	if (pack_everything & ALL_INTO_ONE) {
 		repack_promisor_objects(&po_args, &names);
 
-		if (existing.non_kept_packs.nr && delete_redundant &&
+		if (has_existing_non_kept_packs(&existing) &&
+		    delete_redundant &&
 		    !(pack_everything & PACK_CRUFT)) {
 			for_each_string_list_item(item, &names) {
 				strvec_pushf(&cmd.args, "--keep-pack=%s-%s.pack",