Select the BuildMaster release to trigger build for:
During a build the BUILDMASTER_RELEASE_NUMBER environment variable will be set with this value.
NOTE: if a specific release number is selected (for example an emergency patch might want to go on an earlier release than the latest one) this will become invalid once the release is finalised in BuildMaster. There may be scope for an enhancement here to provide alternative forms of matching on release number - eg by branch name.