--- /dev/null
+#!/bin/sh -eu
+# A target must be rebuilt when a non-existence dependency exists.
+
+>all.do printf 'redo-ifchange a\n'
+>a.do printf 'test -e b || redo-ifcreate b\ndate +%s\n'
+
+redo
+<a read -r timestamp_a1
+
+>b :
+sleep 1
+
+redo
+<a read -r timestamp_a2
+
+test ${timestamp_a2} -gt ${timestamp_a1}