Add a test for the preceding fix (nonexistent directories).

t/autosubdir/clean.do

@@ -0,0 +1,2 @@
+rm -rf *.tmp
+rm -f *~ .*~

t/autosubdir/default.txt.do

@@ -0,0 +1,2 @@
+mkdir -p $(dirname $1)
+echo "hello" >$3

t/autosubdir/test.do

@@ -0,0 +1,3 @@
+rm -rf sub.tmp
+redo-ifchange sub.tmp/test.txt
+[ -e sub.tmp/test.txt ] || exit 96

t/clean.do

@@ -1,5 +1,5 @@
 redo example/clean curse/clean deps/clean "space dir/clean" stamp/clean \
-	defaults-flat/clean defaults-nested/clean
+	defaults-flat/clean defaults-nested/clean autosubdir/clean
 rm -f broken nonshelltest shellfile mode1 makedir.log chdir1 deltest2 \
 	hello [by]ellow *.o *~ .*~ *.log CC LD passfail silence silence.do \
 	touch1 touch1.do always1 ifcreate[12].dep ifcreate[12] *.vartest \

t/test.do

@@ -4,4 +4,4 @@ redo nonshelltest shelltest \
 	deltest deltest2 test.args test2.args passfailtest chdirtest \
 	curse/test deps/test "space dir/test" modetest makedir2 \
 	silencetest touchtest stamp/test alwaystest ifcreate-test \
-	unicode blank/blank vartest atime
+	unicode blank/blank vartest atime autosubdir/test