updating whatsnew

Author: realead

doc/source/whatsnew/v1.4.0.rst

@@ -990,6 +990,7 @@ Other
 - Bug in :meth:`Series.replace` raising ``ValueError`` when using ``regex=True`` with a :class:`Series` containing ``np.nan`` values (:issue:`43344`)
 - Bug in :meth:`DataFrame.to_records` where an incorrect ``n`` was used when missing names were replaced by ``level_n`` (:issue:`44818`)
 - Bug in :meth:`DataFrame.eval` where ``resolvers`` argument was overriding the default resolvers (:issue:`34966`)
+- :meth:`Series.__repr__` no longer replaces all null-values with "NaN" but uses they real string-representations (:issue:`45263`)
 
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