adding can_be_shared

rowers/views/planviews.py

@@ -419,8 +419,11 @@ def plannedsession_multiclone_view(
 def template_share_view(request,id=0,userid=0):
     r = getrequestplanrower(request,userid=userid)
     ps = get_object_or_404(PlannedSession,pk=id)
-    ps.is_public = True
-    ps.save()
+    if ps.can_be_shared:
+        ps.is_public = True
+        ps.save()
+    else:
+        messages.error(request,'This planned session comes from a third party and cannot be shared')
 
     return HttpResponseRedirect(reverse(template_library_view))