Final dist filename change for JRuby 9000.

[headius]

Sorry for the additional change...but as far as I can tell, JRuby 9000 is the only build in here using a snapshot/nightly, and things have been in flux. Once we have releases of 9000 we can update this again and it should be ok.

I would like to clarify, however, how snapshot/nightly builds are supposed to work in ruby-build. As we rev JRuby, the snapshot builds will change.... 9.0.0.1-SNAPSHOT and so on. Should we make the filename the same for snapshots on a given branch or something?

[mislav]

The "dev" builds in ruby-build don't have any special behavior, although there were attempts to improve it by renaming the install directory to contain the current SHA of the branch or date or whatever #334 (comment)

If the snapshot filename and directory inside tarball changes to 9.0.0.1-SNAPSHOT that would be inconvenient because we would need to update ruby-build definition again, and people on the previous version would experience stale installs if 9.0.0.0-SNAPSHOT will stop getting updated in favor of 9.0.0.1. Please give us a heads-up before this happens so we can figure out what we want to do in that scenario.