diff -r 492cd4bbca08 -r 3d0f8918351b mercurial/templater.py
--- a/mercurial/templater.py	Tue Aug 22 17:16:13 2017 -0400
+++ b/mercurial/templater.py	Mon Jul 03 15:33:27 2017 +0200
@@ -18,6 +18,7 @@
     encoding,
     error,
     minirst,
+    obsutil,
     parser,
     pycompat,
     registrar,
@@ -849,6 +850,22 @@
     func = lambda a, b: a % b
     return runarithmetic(context, mapping, (func, args[0], args[1]))
 
+@templatefunc('obsfateverb(successors)')
+def obsfateverb(context, mapping, args):
+    """Compute obsfate related information based on successors (EXPERIMENTAL)"""
+    if len(args) != 1:
+        # i18n: "obsfateverb" is a keyword
+        raise error.ParseError(_("obsfateverb expects one arguments"))
+
+    successors = evalfuncarg(context, mapping, args[0])
+
+    try:
+        return obsutil.successorsetverb(successors)
+    except TypeError:
+        # i18n: "obsfateverb" is a keyword
+        errmsg = _("obsfateverb first argument should be countable")
+        raise error.ParseError(errmsg)
+
 @templatefunc('relpath(path)')
 def relpath(context, mapping, args):
     """Convert a repository-absolute path into a filesystem path relative to