(REST API) Get Full Branch Specifications For VCS Root?

Hello,

Is there an endpoint that exposes the full branch specifications for a VCS root?  (See below for example)
I am attempting to get pending changes through the API for a particular build config, by using %teamcity.build.branch% in the locator.  (Ex: /app/rest/changes?locator=buildType:(id:build_type_ID),pending:true,branch:refs%2Fheads%2Frelease-5.5).

However, this parameter uses the logical branch name, meaning I either have to enforce that all my build configurations do not use logical names, or figure out a way to determine the full branch specification based on the logical branch name.   I do not want to make all of my VCS roots be without logical branch names, but I cannot determine any means of retrieving branch specifications to compare the logical branch name against.  

Is there a resource which I can use to retrieve this information?