BUG: chokes on pd.DatetimeTZDtype if there are no rows.

This is a follow up to pandas-dev#41875

Author: pcorpet

pandas/core/reshape/reshape.py

@@ -291,7 +291,12 @@ def get_new_values(self, values, fill_value=None):
         # if our mask is all True, then we can use our existing dtype
         if mask_all:
             dtype = values.dtype
-            new_values = np.empty(result_shape, dtype=dtype)
+            if isinstance(dtype, ExtensionDtype):
+                # GH#41875
+                cls = dtype.construct_array_type()
+                new_values = cls._empty(result_shape, dtype=dtype)
+            else:
+                new_values = np.empty(result_shape, dtype=dtype)
         else:
             if isinstance(dtype, ExtensionDtype):
                 # GH#41875