-(dir-dir-as-file) begin
-(dir-dir-as-file) mkdir "abc"
-(dir-dir-as-file) create "abc" (must return false)
-(dir-dir-as-file) end
+(dir-over-file) begin
+(dir-over-file) mkdir "abc"
+(dir-over-file) create "abc" (must return false)
+(dir-over-file) end