fix deprecation warning

svn path=/plone.app.discussion/trunk/; revision=48234

plone/app/discussion/comment.py

@@ -19,7 +19,6 @@ from zope.interface import implements
 
 from Acquisition import aq_parent, aq_base, Implicit
 
-from AccessControl.Role import RoleManager
 from OFS.owner import Owned
 
 from persistent import Persistent
@@ -41,6 +40,12 @@ from plone.app.discussion.interfaces import IDiscussionSettings
 from Products.CMFCore.CMFCatalogAware import CatalogAware
 from Products.CMFCore.CMFCatalogAware import WorkflowAware
 
+try:
+    from OFS.role import RoleManager
+except ImportError:
+    # Zope <=2.12
+    from AccessControl.Role import RoleManager
+
 
 COMMENT_TITLE = _(u"comment_title",
     default=u"${creator} on ${content}")