Switched over to the GRCm39 mouse genome build, as well as the v8 annotation file. The v5 and v7 versions are probably no longer available for download from Ensembl, but we have left the option --v7 in there for backward compatibility for the time being.
The documentation and genome preparation do now work with the latest genome annotation file (v8, mgp_REL2021_snps.vcf.gz) from the Mouse Genomes Project.