* Simplify communication with the hook a bit (don't use file

descriptors 3/4, just use stdin/stderr).

tests/build-hook.hook.sh

@@ -11,11 +11,11 @@ outPath=$(sed 's/Derive(\[("out",\"\([^\"]*\)\".*/\1/' $drv)
 echo "output path is $outPath" >&2
 
 if $(echo $outPath | grep -q input-1); then
-    echo "accept" >&3
-    read x <&4
+    echo "# accept" >&2
+    read x
     echo "got $x"
     mkdir $outPath
     echo "BAR" > $outPath/foo
 else
-    echo "decline" >&3
+    echo "# decline" >&2
 fi