Updating logstash plugins takes forever

I'm trying to use logstash-plugin update and it does some stuff (showing the plugins, asking for major version upgrades, downloading something) but then it's just stuck at 100% CPU. Is it supposed to take that long. I've let it run for 30 minutes and it's just eating CPU.

The stacktrace shows it's somewhere in the bundler dependency resolution.

This is on a AMD 4.4GHz CPU, Linux Container, so near native performance.

Logstash 2.3.4. Installing a local plugin is very fast.