Team City Symbol Server plugin. Location of source code on server?

Hello,

Could you please tell me where eventually the original source code is fetched from while debugging using Team City source indexer? As I can see from indexed pdb file it fetches it from <Teamcity_url>/app/builds/id-<build_number>/sources/files/<relative_path_to_sourcefile>. But how is the response for this request formed on server? Does it take the exact version of source file from VCS revision used for that particular build (for example GIT in my case)?

Thanks