Now, as the project is in stabilization phase for the 2.4 release, the nightlies referred from the website are built from master, including (presumably unstable) changes for 2.5.
By tweaking the download URL I found some recent 2.4 builds that seem to come from the release branch at https://services.gradle.org/distributions-snapshots , but would have been nicer if there was a direct link for them too.