add GH issue # to tests

Author: Nico Cernek

pandas/tests/reshape/merge/test_merge.py

@@ -2097,6 +2097,7 @@ def test_merge_equal_cat_dtypes2():
 
 
 def test_right_merge_preserves_row_order():
+    # GH 27453
     population = [
         ("Jenn", "Jamaica", 3),
         ("Beth", "Bulgaria", 7),
@@ -2123,6 +2124,7 @@ def test_right_merge_preserves_row_order():
 
 
 def test_left_merge_preserves_row_order():
+    # GH 27453
     population = [
         ("Jenn", "Jamaica", 3),
         ("Beth", "Bulgaria", 7),