At our site we often test operating system that are not releases, so the names are not only OS.MAJOR.MINOR, but various others, e.g. OS.MAJOR.MINOR.TIMESTAMP or OS.MAJOR.BETA.
This means current model cannot allow this setup.

A workaround would be to directly edit db entries for filenames, rename filenames to our needs and hope no validator goes through data that already is inside db.
But a better solution would be to revisit model design.

• conservative: add an optional attribute "suffix"
• revisionist: refactor OperatingSystem as follows:
  • remove use of major-minor semantics, just use description
  • i.e. cleanup searches related by that
  • filenames should be created by converter of description field->legal path [e.g. by downcase and replace ' '->'-']

The conservative approach is ... tactical, and relatively easy to implement. but It might hit another wall in the future.