fix: dont send if start == end

zfs_backup.py

@@ -66,6 +66,8 @@ class Manager:
                 stream = self._send_absolute(local_dataset)
             else:
                 stream = self._send_incremental(local_dataset, remote_dataset)
+                if stream is None:
+                    continue
             ZFS.receive(stream, self._external_pool)
 
     def _get_user_filtered_dataset_backup_map(self) -> _map_type:
@@ -97,12 +99,14 @@ class Manager:
 
     def _send_incremental(
         self, local_dataset: Dataset, remote_dataset: Dataset
-    ) -> Popen:
+    ) -> Popen | None:
         """Send incremental stream between two datasets to remote."""
         start_snapshot = self._get_newest_common_snapshot_with_backup_tags(
             local_dataset, remote_dataset
         )
         end_snapshot = self._get_newest_snapshot_with_backup_tag(local_dataset)
+        if start_snapshot == end_snapshot:
+            return None
         stream = ZFS.send_incremental(start_snapshot, end_snapshot)
         return stream
 
@@ -742,6 +746,9 @@ class Snapshot:
     def __repr__(self):
         return str(self._path)
 
+    def __eq__(self, other: ZFSPath):
+        return self._path == other._path
+
     def newer_than(self, other: Snapshot) -> bool:
         return self > other