Usage scenario

In the nf-core CI testing, we want to test pipelines with the absolute latest version of Nextflow to ensure that the pipeline will work with any upcoming releases. So we use NXF_EDGE for this. However, sometimes the edge release of Nextflow is actually older than the most recent stable release, which has nasty unintended effects. As such, we're forced to manually comment out and re-comment the NXF_EDGE variable in our CI over time as the releases come and go.

Suggest implementation

If NXF_EDGE is specified, take the latest stable release or the latest edge release - which ever is most recent.