mirror update
If a commit introduced a new Ruby definition, we want it mirrored even if there might have been an accidental failure on CI.
Grep mustn't get invoked with 0 parameters, otherwise it will hang waiting on stdin.
When new Ruby definitions get added, our current CloudFront mirror may get out of date. This adds a task to the CI process that detects added/changed package URLs and uploads them to our S3 bucket. Fixes #392, references #395