Be able to concatenate manual version with automated version

Hi

There are some cases when you are not develop your own project but for example make conf changes and you would like to combine the original project version with yours.

For example, we are using Filebeat, and we pack it with our config file, so we are not forking it but just docker FROM filebeat:VERSION it, and as a result we would like to be able to concatenate Filebeat version and the internal version, something like that REGISTRY_URL/elastic/filebeat:1.2.3-filebeat-5.5.1 while the first version is internal and the second is for the original. The original version could be branch / gitlab variable, but anyway value that can be taken from and exposed during the CI pipeline.

Do you think this simple to implement?

Thanks D.