--- a/mercurial/templatekw.py	Mon Jan 21 15:29:14 2019 +0000
+++ b/mercurial/templatekw.py	Fri Jan 25 23:36:23 2019 -0800
@@ -796,7 +796,7 @@
     substate = ctx.substate
     if not substate:
         return compatlist(context, mapping, 'subrepo', [])
-    psubstate = ctx.parents()[0].substate or {}
+    psubstate = ctx.p1().substate or {}
     subrepos = []
     for sub in substate:
         if sub not in psubstate or substate[sub] != psubstate[sub]: