FIX don't compare things that can be arrays to strings.

sklearn/metrics/regression.py

@@ -352,6 +352,7 @@ def explained_variance_score(y_true, y_pred,
     output_scores[valid_score] = 1 - (numerator[valid_score] /
                                       denominator[valid_score])
     output_scores[nonzero_numerator & ~nonzero_denominator] = 0.
+    if isinstance(multioutput, string_types):
         if multioutput == 'raw_values':
             # return scores individually
             return output_scores
@@ -393,8 +394,9 @@ def r2_score(y_true, y_pred,
                 'variance_weighted'] or None or array-like of shape (n_outputs)
         Defines aggregating of multiple output scores.
         Array-like value defines weights used to average scores.
-        Default value correponds to 'variance_weighted', but
-        will be changed to 'uniform_average' in next versions.
+        Default value correponds to 'variance_weighted', this behaviour is
+        deprecated since version 0.17 and will be changed to 'uniform_average'
+        starting from 0.19.
 
         'raw_values' :
             Returns a full set of scores in case of multioutput input.