[PATCH v4 2/2] index: raise a bug if the index is materialised more than once

["Anh Le via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Anh Le <anh@xxxxxxxxx>

If clear_skip_worktree_from_present_files() encounter a sparse directory,
it fully materialise the index which should expand any sparse directories
and start going through each entries again. If this happens more than once,
raise it with a BUG.

Signed-off-by: Anh Le <anh@xxxxxxxxx>
---
 sparse-index.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sparse-index.c b/sparse-index.c
index 8713a15611d..8c269dab803 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -510,6 +510,8 @@ restart:
 			path_count[restarted]++;
 			if (path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
 				if (S_ISSPARSEDIR(ce->ce_mode)) {
+					if (restarted)
+						BUG("ensure-full-index did not fully flatten?");
 					ensure_full_index(istate);
 					restarted = 1;
 					goto restart;
-- 
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