@Mastodon

this may be useful for some here:
If during the build phase on docker you encounter
```
Bundler::HTTPError Could not fetch specs from https://rubygems.org/ due to underlying error <Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)>
```
Then an unsatisfactory workaround is to temporarily disable IPv6 on your docker daemon.