Fixed bug in mpas_stream_list_insert.

Author: amstokely

src/framework/mpas_stream_list.F

@@ -118,12 +118,15 @@ subroutine MPAS_stream_list_insert(list, stream, ierr) !{{{
             list % head => stream
         else
             node => list % head
-            do while (associated(node % next))
+            do while (associated(node))
                 if (node % name == stream % name) then
                     if (present(ierr)) ierr = MPAS_STREAM_LIST_DUPLICATE
-                    LIST_ERROR_WRITE('Found duplicate item '//trim(stream % name)//' in list.')
                     return
                 end if
+                if (.not. associated(node % next)) then
+                    node % next => stream
+                    exit
+                end if
                 node => node % next
             end do
             node % next => stream