`join-datagen.R` expects 4 arguments but only 3 are provided in `format_and_mount` script

Here is a part of `format_and_mount.sh`:

```
echo "Creating 500mb join datasets"
Rscript ../_data/join-datagen.R 1e7 0 0
Rscript ../_data/join-datagen.R 1e7 5 0
Rscript ../_data/join-datagen.R 1e7 0 1
```

This fails:

```
Creating 500mb join datasets
Error: sort %in% c(0L, 1L) is not TRUE
Execution halted
```

`join-datagen.R` expects 4 arguments but only 3 are provided.