t/deps/dirtest: test correct dependency checking for targets named 'dirname'

We had a bug (fixed in the previous commit) where doing 'redo-ifchange
dirname' (which runs dirname/all.do) would not create the stamp correctly,
so that it would always show up as dirty.

It's a little bit complicated to simulate, but this does it.

t/deps/dirtest/.gitignore

@@ -0,0 +1,2 @@
+log
+dir1/stinky

t/deps/dirtest/clean.do

@@ -0,0 +1 @@
+rm -f *~ .*~ dir1/*~ dir1/.*~ dir1/stinky dir1/log log

t/deps/dirtest/dir1/all.do

@@ -0,0 +1,2 @@
+redo-ifchange stinky
+echo $$ >>log

t/deps/dirtest/dir1/stinky.do

@@ -0,0 +1 @@
+echo "I'm stinky"

t/deps/dirtest/t1.do

@@ -0,0 +1,2 @@
+redo-ifchange dir1/
+echo $$ >>log

t/deps/dirtest/t2.do

@@ -0,0 +1,2 @@
+redo-ifchange dir1
+echo $$ >>log

t/deps/dirtest/t3.do

@@ -0,0 +1,2 @@
+redo-ifchange dir1/all
+echo $$ >>log

t/deps/dirtest/test.do

@@ -0,0 +1,19 @@
+touch t?.do
+for first in t1 t2 t3; do
+	for second in t1 t2 t3; do
+		rm -f log dir1/log dir1/stinky
+		. ../../flush-cache.sh
+		redo $first
+		touch $second.do
+		. ../../flush-cache.sh
+		redo $second
+		. ../../flush-cache.sh
+		redo-ifchange $second
+		C1="$(wc -l <dir1/log)"
+		C2="$(wc -l <log)"
+		if [ "$C1" != 1 -o "$C2" != 2 ]; then
+			echo "failed: $first>$second, c1=$C1, c2=$C2" >&2
+			exit 55
+		fi
+	done
+done

t/deps/test.do

@@ -1 +1,2 @@
-redo test1 test2 ifchange-fail overwrite basic/test
+redo test1 test2 ifchange-fail overwrite basic/test dirtest/test
+