Moved whatsnew to v.0.21.0

doc/source/whatsnew/v0.20.0.txt

@@ -1731,4 +1731,3 @@ Other
 - Compat for 32-bit platforms for ``.qcut/cut``; bins will now be ``int64`` dtype (:issue:`14866`)
 - Bug in interactions with ``Qt`` when a ``QtApplication`` already exists (:issue:`14372`)
 - Avoid use of ``np.finfo()`` during ``import pandas`` removed to mitigate deadlock on Python GIL misuse (:issue:`14641`)
-- Bug in ``DataFrame.rank()`` and ``Series.rank()`` when ``method='dense'`` and ``pct=True`` (:issue:`15630`)

doc/source/whatsnew/v0.23.0.txt

@@ -905,6 +905,7 @@ Offsets
 
 Numeric
 ^^^^^^^
+- Bug in ``DataFrame.rank()`` and ``Series.rank()`` when ``method='dense'`` and ``pct=True`` (:issue:`15630`)
 - Bug in :class:`Series` constructor with an int or float list where specifying ``dtype=str``, ``dtype='str'`` or ``dtype='U'`` failed to convert the data elements to strings (:issue:`16605`)
 - Bug in :class:`Index` multiplication and division methods where operating with a ``Series`` would return an ``Index`` object instead of a ``Series`` object (:issue:`19042`)
 - Bug in the :class:`DataFrame` constructor in which data containing very large positive or very large negative numbers was causing ``OverflowError`` (:issue:`18584`)

pandas/tests/frame/test_rank.py

@@ -1,18 +1,16 @@
 # -*- coding: utf-8 -*-
 import pytest
-from datetime import timedelta, datetime
-from distutils.version import LooseVersion
-from numpy import nan
 import numpy as np
+import pandas.util.testing as tm
 
-from pandas import Series, DataFrame
-
-import pytest
+from distutils.version import LooseVersion
+from datetime import timedelta, datetime
+from numpy import nan
 
-from pandas.compat import product
 from pandas.util.testing import assert_frame_equal
-import pandas.util.testing as tm
 from pandas.tests.frame.common import TestData
+from pandas import Series, DataFrame
+from pandas.compat import product
 
 
 class TestRank(TestData):