Support for versions defined via a var?

[glenjamin]

I'm not sure how doable this will be, but I figured I'd post it anyway.

We have some libraries which are published as a bundle, and the consumer should use the same version of each of them (there are other modules also published in the the bundle, and different projects pick different subsets).

This is generally managed by using a var in the project.clj

(def bundle-version "0.1.1231")

(defproject application "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"

  :dependencies [[org.clojure/clojure "1.10.0"]
                 [org.clojure/core.async "0.4.490"]

                 [bundled/bundle-core ~bundle-version]
                 [bundled/bundle-postgresql ~bundle-version]])

However these get skipped over entirely by lein ancient - I am able to use show-latest manually to check and update these, but it would be nice if ancient were able to read these values.