ensure value is not np.nan

Author: Matt Roeschke

pandas/io/formats/format.py

@@ -947,7 +947,7 @@ def _format(x):
             if self.na_rep is not None and is_scalar(x) and isna(x):
                 if x is None:
                     return 'None'
-                elif x is NaT or is_null_datetimelike(x):
+                elif x is NaT or (is_null_datetimelike(x) and not np.isnan(x)):
                     return 'NaT'
                 return self.na_rep
             elif isinstance(x, PandasObject):