Set the ManifestEntryStatus (apache#2408)

A faulty refactor:


apache@59742e0#diff-e9df836e263024ba54e2706853fb25c00269fbfe3726b440ba57f4a929c995dcR927

This produces incorrect metadata, but was hidden by the writer.

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# Rationale for this change

## Are these changes tested?

## Are there any user-facing changes?

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---------

Co-authored-by: Kevin Liu <[email protected]>

Author: Fokko

pyiceberg/manifest.py

@@ -1087,18 +1087,15 @@ def add_entry(self, entry: ManifestEntry) -> ManifestWriter:
         return self
 
     def add(self, entry: ManifestEntry) -> ManifestWriter:
-        if entry.sequence_number is not None and entry.sequence_number >= 0:
-            self.add_entry(
-                ManifestEntry.from_args(
-                    snapshot_id=self._snapshot_id, sequence_number=entry.sequence_number, data_file=entry.data_file
-                )
-            )
-        else:
-            self.add_entry(
-                ManifestEntry.from_args(
-                    status=ManifestEntryStatus.ADDED, snapshot_id=self._snapshot_id, data_file=entry.data_file
-                )
+        self.add_entry(
+            ManifestEntry.from_args(
+                status=ManifestEntryStatus.ADDED,
+                snapshot_id=self._snapshot_id,
+                sequence_number=entry.sequence_number if entry.sequence_number != UNASSIGNED_SEQ else None,
+                data_file=entry.data_file,
             )
+        )
+
         return self
 
     def delete(self, entry: ManifestEntry) -> ManifestWriter:

tests/catalog/test_sql.py

@@ -1657,6 +1657,10 @@ def test_merge_manifests_local_file_system(catalog: SqlCatalog, arrow_table_with
         tbl.append(arrow_table_with_null)
 
     assert len(tbl.scan().to_arrow()) == 5 * len(arrow_table_with_null)
+    current_snapshot = tbl.current_snapshot()
+    assert current_snapshot
+    manifests = current_snapshot.manifests(tbl.io)
+    assert len(manifests) == 1
 
 
 @pytest.mark.parametrize(