Merge branch 'ds/maintenance-prefetch-fix'

The prefetch task in "git maintenance" assumed that "git fetch" from any remote would fetch all its local branches, which would fetch too much if the user is interested in only a subset of branches there. * ds/maintenance-prefetch-fix: maintenance: respect remote.*.skipFetchAll maintenance: use 'git fetch --prefetch' fetch: add --prefetch option maintenance: simplify prefetch logic