request_splitter: add strategy_do_non_bootstrapped().

Utilize in select command to fallback to none strategy and also excluded
packages that require bootstrapping.

osc-staging.py

@@ -371,6 +371,7 @@ def do_staging(self, subcmd, opts, *args):
                         # Merge any none strategies before final none strategy.
                         splitter.merge(strategy_none=True)
                     splitter.strategy_do('none')
+                    splitter.strategy_do_non_bootstrapped('none')
 
                 proposal = splitter.proposal
                 if len(proposal) == 0:

osclib/request_splitter.py

@@ -298,6 +298,12 @@ class RequestSplitter(object):
         self.split()
         self.propose_assignment()
 
+    def strategy_do_non_bootstrapped(self, name, **kwargs):
+        self.strategy_set(name, **kwargs)
+        self.filter_add('./action/target[not(starts-with(@ring, "0"))]')
+        self.split()
+        self.propose_assignment()
+
     def filter_grouped(self, groups):
         for group in sorted(self.grouped.keys()):
             if group not in groups: