The part of the lfs store that requires a destination cannot operate on multiple destination (yet). So we move them to the dedicated APIs.
I was a bit confused about the comment initially, but I now understand is probably about the fact ui.expandpath(b'default') would return b'default' if no default path is defined. However the comment does not match the code I replaced.
Since I already document the "issue" in urlutil (later in the series) I'll mostly drop this comment.