Fix autounmask/sub-slot interference, bug #459832
depgraph._set_args: fix atom_arg_map for refs > 1

Due to an indentation error, atom_arg_map only preserved a single
set reference, preventing slot-operator rebuilds from triggering
for atoms that were also pulled in via another set such as world.
repoman: check metadata.xml doctype, bug #328113
repoman: remove unused grouplist function