At the moment, when pull request is opened, on details page of the pull request you see the result of the build for the head of source branch.
Unfortunately it doesn't show you the build status for codebase after pull request is merged even though, internally Stash keeps the references to pull request merge.

There is a plugin for it (https://marketplace.atlassian.com/plugins/com.bolyuba.stash.plugin.stash-build-status-plugin) but it won't work with Stash-Bamboo integration and still requires custom status report of the build result.

It would be nice to:
1. Allow bamboo to build from successful result of pull request internal branch
2. Report this to pull request to person who is about to merge it can see how the build will look like.

Regards,
Alex Krupnov