Build variables not available in Deployments

According to our documentation, Bamboo should make snapshots of values for plan variables available for deployment releases, but this is not happening.

Steps to reproduce:

1. Define a variable in Plan Configuration > Variables tab.
2. Run the build at least once.
3. Open the build result Metadata tab, and verify that the variable is listed.
4. Create a deployment project and deploy it.
5. On the deployment results page, click on the release version link
6. Click on the Variables tab, and verify that the variable defined in the regular build is not listed.