Generic registry - allow filenames with tilde in them

Proposal

Enable the use of files with tilde (~) in the filename in the generic repository. This use case is supported by grub releases that include tildes in their filenames: https://alpha.gnu.org/gnu/grub/

This allows the generic registry to contain upstream source bundles. This is particularly useful for embedded Linux projects that need to maintain their own caches of upstream source bundles.