reconciler: Fix reconciler lumping unmatched books items together (#20737)

Issue was that the subset matching was passing through the grouped transactions
rather than the original transactions when it failed to match.

conservancy_beancount/reconcile/statement_reconciler.py

@@ -503,7 +503,7 @@ def subset_match(
             if best_match_index is not None:
                 del statement_trans[best_match_index]
         else:
-            remaining_books_trans.append(r2)
+            remaining_books_trans.extend(group_items)
     for r1 in statement_trans:
         remaining_statement_trans.append(r1)
     return matches, remaining_statement_trans, remaining_books_trans

tests/test_reconcile.py

@@ -350,6 +350,33 @@ def test_subset_passes_through_all_non_matches():
     )
 
 
+def test_subset_passes_though_unmatched_transactions_with_same_payee():
+    # Tracy noticed that when multiple books payments had the same date and
+    # payee and were unmatched, they were being displayed lumped together, when
+    # they should have remained separate.
+    B1a = {
+        'date': datetime.date(2022, 1, 1),
+        'amount': decimal.Decimal('100.00'),
+        'payee': 'Hannah',
+        'check_id': '',
+        'filename': '2022/imports.beancount',
+        'line': 777,
+        'bank_statement': '',
+    }
+    B1b = {
+        'date': datetime.date(2022, 1, 1),
+        'amount': decimal.Decimal('100.00'),
+        'payee': 'Hannah',
+        'check_id': '',
+        'filename': '2022/imports.beancount',
+        'line': 797,
+        'bank_statement': '',
+    }
+    assert subset_match([], [B1a, B1b]) == (
+        [], [], [B1a, B1b],  # No match: two preserved intact
+    )
+
+
 def test_handles_amex_csv():
     CSV = """Date,Receipt,Description,Card Member,Account #,Amount,Extended Details,Appears On Your Statement As,Address,City/State,Zip Code,Country,Reference,Category\n08/19/2021,,Gandi.net           San Francisco,RODNEY R BROWN,-99999,28.15,"00000009999 00000009999999999999\nGandi.net\nSan Francisco\n00000009999999999999",Gandi.net           San Francisco,"NEPTUNUSSTRAAT 41-63\nHOOFDDORP",,2132 JA,NETHERLANDS (THE),'999999999999999999',Merchandise & Supplies-Internet Purchase\n"""
     expected = [