--- a/mercurial/cext/revlog.c	Wed Aug 08 21:52:39 2018 -0700
+++ b/mercurial/cext/revlog.c	Wed Aug 08 22:26:57 2018 -0700
@@ -1075,10 +1075,6 @@
 		return -1;
 	}
 	self->length = 1;
-	if (nt_insert(self, nullid, -1) == -1) {
-		free(self->nodes);
-		return -1;
-	}
 	return 0;
 }
 
@@ -1152,6 +1148,11 @@
 			self->nt = NULL;
 			return -1;
 		}
+		if (nt_insert(self->nt, nullid, -1) == -1) {
+			PyMem_Free(self->nt);
+			self->nt = NULL;
+			return -1;
+		}
 		self->ntrev = (int)index_length(self);
 		self->ntlookups = 1;
 		self->ntmisses = 0;