Fixes #10566. Reverts part of 3a51b83 to improve channel changes.
The first half of 3a51b83 looks like a bug (the new condition means the following "else if" branch is never taken). Removing it stops guide-based channel changes from being forced onto a different tuner. Note: this fix exposes another problem with guide-based channel changes - you can't switch to a different tuner in the current input group. Fix is in progress.