diff -r 546dc42c3bc4 -r 448f7ec247e2 mercurial/hgweb/webcommands.py
--- a/mercurial/hgweb/webcommands.py	Sun Mar 18 21:46:20 2018 +0900
+++ b/mercurial/hgweb/webcommands.py	Sun Mar 18 21:18:57 2018 +0900
@@ -1082,7 +1082,7 @@
         linerange = webutil.formatlinerange(*lrange)
         # deactivate numeric nav links when linerange is specified as this
         # would required a dedicated "revnav" class
-        nav = None
+        nav = []
         if descend:
             it = dagop.blockdescendants(fctx, *lrange)
         else: