fix(table): avoid committing update builders after exceptions (#3354)

## Summary

Avoid committing update builders when the body of a `with` block raises.

`UpdateTableMetadata.__exit__` currently commits unconditionally, so
user code like `with table.update_schema() as update:` can still mutate
table metadata even when an exception is raised before the block
finishes. This change makes update builders mirror
`Transaction.__exit__` and only commit on a clean exit.

## Testing

- `.venv\\Scripts\\python -m pytest
"tests/catalog/test_catalog_behaviors.py::test_update_schema_with_statement_does_not_commit_on_exception[memory]"
"tests/catalog/test_catalog_behaviors.py::test_update_schema_with_statement_does_not_commit_on_exception[sql]"
-q`

Author: fallintoplace

pyiceberg/table/update/__init__.py

@@ -21,6 +21,7 @@
 from abc import ABC, abstractmethod
 from datetime import datetime
 from functools import singledispatch
+from types import TracebackType
 from typing import TYPE_CHECKING, Annotated, Any, Generic, Literal, TypeVar, cast
 
 from pydantic import Field, field_validator, model_serializer, model_validator
@@ -71,9 +72,10 @@ def _commit(self) -> UpdatesAndRequirements: ...
     def commit(self) -> None:
         self._transaction._apply(*self._commit())
 
-    def __exit__(self, _: Any, value: Any, traceback: Any) -> None:
-        """Close and commit the change."""
-        self.commit()
+    def __exit__(self, exctype: type[BaseException] | None, excinst: BaseException | None, exctb: TracebackType | None) -> None:
+        """Close and commit the change if no exceptions have been raised."""
+        if exctype is None and excinst is None and exctb is None:
+            self.commit()
 
     def __enter__(self) -> U:
         """Update the table."""

tests/catalog/test_catalog_behaviors.py

@@ -942,6 +942,26 @@ def test_add_column_with_statement(catalog: Catalog, table_schema_simple: Schema
     assert table.schema().schema_id == 2
 
 
+def test_update_schema_with_statement_does_not_commit_on_exception(
+    catalog: Catalog, table_schema_simple: Schema, random_table_identifier: Identifier
+) -> None:
+    namespace = Catalog.namespace_from(random_table_identifier)
+    catalog.create_namespace(namespace)
+    table = catalog.create_table(random_table_identifier, table_schema_simple)
+
+    with pytest.raises(ValueError):
+        with table.update_schema() as tx:
+            tx.add_column(path="should_not_commit", field_type=IntegerType())
+            int("boom")
+
+    assert table.schema() == table_schema_simple
+    assert table.schema().schema_id == 0
+
+    reloaded = catalog.load_table(random_table_identifier)
+    assert reloaded.schema() == table_schema_simple
+    assert reloaded.schema().schema_id == 0
+
+
 # Namespace tests