ikiwiki hosting internals/ todo/ avoid third checkout of source for setup branch

The setup branch is checked out into a site user's home directory, and this means that ~/.git is another copy of the source, on top of the two in source/.git and source.git. This can use a lot of space, although often nothing pulls updates to mater into that repo if lucky.

git has ways now to avoid this problem, eg multiple worktrees. --Joey