Expose Release SCM Branch and Release SCM Tag as build variables

when using "Artifactory Release Staging", one of the things which is suggested by the plugin is the "VCS Tag Name/URL".
It would be nice to have this value exposed as an environment variable so we can use it.

Concrete case: we pass the SVN_URL from the main job to the downstream job to be sure to checkout the same revision; this principle works fine, yet not when releasing...

When releasing, the main job gets (1) a release version and (2) gets tagged, while the downstream job gets the original SVN_URL (on trunk, with snapshot version).

also see:
http://forums.jfrog.org/Jenkins-plugin-Environment-property-for-Release-Tag-td7578637.html