--- /dev/null
+#!/bin/sh
+
+. ./tests/lib/test-setup.sh
+
+foo_setup
+
+(
+ cd "$repo"
+ git checkout -b historical
+ git checkout master
+ echo Other contents > other-file
+ git add other-file
+ git commit -m 'Second commit message'
+)
+
+python3 ./pinch.py pin "$conf"
+
+sed -i 's/master/historical/' "$conf"
+
+if python3 ./pinch.py pin "$conf";then
+ echo "FAIL: non-ancestor commit should be rejected"
+ exit 1
+else
+ echo PASS
+fi