When selecting a branch to compare there is a possibility of being given a search string that does not result in any matches.

No matches

When in this state, the return key should be disabled. Although pressing return doesn't have any show-stopping effects, it puts the compare tab in a weird state.

Ahead/Behind tabs missing when in branch compare mode

This is a UI behavior was not included in the main branch for this feature because it was not a part of the original feature.

For additional context, check out #4182.