@stephenw10:
Where are you seeing this string? In the logs? Only the base URL should appear in the autoupdate settings. That does mean a space would be very easy to overlook though.
That's exactly what I was thinking, given that is separate, it'd be easy to slip an extra space into a log somewhere. But grepping through the source, I don't see anywhere that would happen.
It definitely doesn't happen in any of the code that actually downloads and installs the updates. There might be a cosmetic bug somewhere where it's slipping in a space in the displayed URL, but I'm not seeing that either.