When reloading a modified source from sourcedir which is ordered before
the original source (e.g. maxpoll was decreased), the new source is
added before the original one is removed. If the source is specified by
IP address, the addition fails due to the conflict with the original
source. Sources specified by hostname don't conflict. They are resolved
later (repeatedly if the resolver provides only conflicting addresses).
Split the processing of sorted source lists into two phases, so all
modified sources are removed before they are added again to avoid the
conflict.
Reported-by: Thomas Lange <thomas@corelatus.se>
