diff -r 995617c7f2fc -r 8dd5200b4086 src/topic/destination.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/topic/destination.py	Wed Oct 21 01:12:32 2015 +0200
@@ -0,0 +1,19 @@
+from mercurial import revset
+from mercurial import error
+def ngtip(repo, branch, all=False):
+    """tip new generation"""
+    ## search for untopiced heads of branch
+    # could be heads((::branch(x) - topic()))
+    # but that is expensive
+    #
+    # we should write plain code instead
+    subquery = '''heads(
+                    parents(
+                       ancestor(
+                         (head() and branch(%s)
+                         or (topic() and branch(%s)))))
+                   ::(head() and branch(%s))
+                   - topic())'''
+    if not all:
+        subquery = 'max(%s)' % subquery
+    return repo.revs(subquery, branch, branch, branch)