For user builds, use a release build id in the description if one exists

Companion change to Ic5913e587400dd38c04aa05de3a7becced77a59e

Change-Id: If5edbf56d567701f96f0ba46af9a90ffa8310c24
Merge pull request #2 from CyanogenMod/cm-10.2

For user builds, use a release build id in the description if one exists