Mention duplicated values in warning messages.

theano/configdefaults.py

@@ -776,9 +776,9 @@ AddConfigVar('warn.round',
 AddConfigVar(
     'warn.inc_subtensor1_opt',
     "Warn if previous versions of Theano (before 0.10) could have "
-    "given incorrect results for inc_subtensor when indexing with "
-    "one array of integers. An incorrect optimization was applied "
-    "when computing set_subtensor(zeros[idx], x)[idx].",
+    "given incorrect results when computing "
+    "inc_subtensor(zeros[idx], x)[idx], when idx is an array of integers "
+    "with duplicated values.",
     BoolParam(warn_default('0.10')),
     in_c_key=False)
 

theano/tensor/opt.py

@@ -3514,7 +3514,11 @@ def local_adv_sub1_adv_inc_sub1(node):
                 'Your current code is fine, but Theano versions '
                 'between 0.7rc1 and 0.10 (or development versions '
                 'between Nov. 2014 and May 2017) '
-                'might have given incorrect results. '
+                'might have given incorrect results. This graph has '
+                'following pattern: inc_subtensor(zeros[idx], x)[idx], '
+                'where idx is an array of integers. This used to be '
+                'optimized to "x", which is incorrect if there are '
+                'duplicated indices in idx. '
                 'To disable this warning, set the Theano flag '
                 'warn.inc_subtensor1_opt to False.')
         return