[PATCH proxmox-backup] fix #8003: sync: pull: log skipped chunk reuse for corrupt manifests

[Christian Ebner <c.ebner@proxmox.com>]

Chunks from a manifest with verify state failed cannot be re-used
since it is not known which chunks are corrupt and/or whether the
index files referenced in the manifest are corrupt. The manifest
is therefore skipped when determining the chunks from the
previous snapshot during sync pull jobs. This was however not logged,
causuing confusion on why a sync job now takes much longer.

Add an additional log line to clarify this.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
---
 src/server/pull.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/server/pull.rs b/src/server/pull.rs
index 4eb5bcf11..13f4f5b09 100644
--- a/src/server/pull.rs
+++ b/src/server/pull.rs
@@ -1273,7 +1273,12 @@ async fn pull_group(
             })?;
 
             match manifest.verify_state()? {
-                Some(verify_state) if verify_state.state == VerifyState::Failed => (),
+                Some(verify_state) if verify_state.state == VerifyState::Failed => {
+                    bail!(
+                        "cannot safely reuse chunks of snapshot {}, verify state failed",
+                        info.backup_dir.backup_time_string(),
+                    );
+                }
                 _ => {
                     for file in manifest.files() {
                         let index: Box<dyn IndexFile> = match file.filename.archive_type() {
-- 
2.47.3