This looks to be unmaintained by upstream since 2014: https://code.google.com/archive/p/mango-doc/source/default/commits I suggest we remove it on that basis. If the dependency remains for current versions of (cilium-proxy envoy-proxy istio-proxy) I could begin patching the errors starting with: ./go/src/code.google.com/p/mango-doc/man3.go:296:9: Errorf format %#v reads arg #2, but call has 1 arg