diff -r f0a62afd1e40 -r 78d9a7b7cdb6 mercurial/extensions.py
--- a/mercurial/extensions.py	Tue Oct 17 10:25:32 2017 -0700
+++ b/mercurial/extensions.py	Tue Oct 17 10:31:44 2017 -0700
@@ -182,7 +182,7 @@
         try:
             uisetup(ui)
         except Exception as inst:
-            ui.traceback()
+            ui.traceback(force=True)
             msg = util.forcebytestr(inst)
             ui.warn(_("*** failed to set up extension %s: %s\n") % (name, msg))
             return False
@@ -203,7 +203,7 @@
                     raise
                 extsetup() # old extsetup with no ui argument
         except Exception as inst:
-            ui.traceback()
+            ui.traceback(force=True)
             msg = util.forcebytestr(inst)
             ui.warn(_("*** failed to set up extension %s: %s\n") % (name, msg))
             return False