Cannot access builds tab if fromRepo is a private fork

Issue Summary

When accessing the builds tab with the fromRepo being a private fork an error dialogue is displaced indicating the resource is not accessible (see below).

Steps to Reproduce

1. Create a personal fork but give no other user access
2. Creating a pull request from that fork to the upstream
3. Log in as a different user who does not have access to the private fork
4. Attempt to view the builds tab in the pull request

Expected Results

You can see the builds listed.

Actual Results

Error dialogue:

Workaround

Upgrade to 7.4.1 or above. 

Alternatively, make the source repository (private fork) accessible to the user trying to view the builds tab.