Clicking View Source from the Branch view always displays the 'main branch' contents on initial load (BB-9722)

To reproduce this, do the following:

• Create two branches with different data
• Go to the branch view
• Select any branch with different data than the 'main branch'
• From the single branch view, select 'View Source'

Observe that the file contents of the main branch are shown and not the contents of that branch. To convince it to display properly, you'll need to re-select the branch from the drop down.