T9044 restricted ocaml-protoc / pbrt version to < 3, due to a misunderstanding by the automated checker. The restriction that is needed is version < 4, since the recent release causes problems with regenerating *.pbt files. This is due to the major change in 4.x merging mutable and immutable types. The automation confused our use of Google protobuf version (proto2) with ocaml-protoc version 3. In fact, updating vyconf *_pbt files for use with version 3.1.1 was one of the many initial updates when first including vyconf into vyos-1x.
Version 3.1.1 is the version tested and stable for vyconf, pending updates for use with versions >= 4.x. Restore version for now.