--- a/hgext3rd/topic/compat.py	Fri Oct 13 20:28:21 2017 +0200
+++ b/hgext3rd/topic/compat.py	Sat Oct 14 20:17:25 2017 +0530
@@ -22,3 +22,10 @@
     getmarkers = obsolete.getmarkers
 if successorssets is None:
     successorssets = obsolete.successorssets
+
+def startpager(ui, cmd):
+    """function to start a pager in case ui.pager() exists"""
+    try:
+        ui.pager(cmd)
+    except AttributeError:
+        pass