adding in test and decrement if we're changing away from a forker.

src/lib/Components/system/base_pg_manager.py

@@ -175,6 +175,7 @@ class ProcessGroupManager(object): #degenerate with ProcessMonitor.
                 except ComponentLookupError:
                     # Retry this with a different forker, if we run out of forkers, then this startup fails.
                     self.forker_reachable[process_group.forker] = False
+                    self.forker_taskcounts[process_group.forker] -= 1 #decrement since we failed to use this forker.
                     try:
                         process_group.forker = self._select_forker(process_group.jobid)
                     except RuntimeError as err:

testsuite/TestCobalt/TestComponents/test_process_manager.py

@@ -167,6 +167,8 @@ class TestProcessManager(object):
         assert self.process_manager.process_groups[1].startup_timeout == 0, (
                 "startup_timeout not reset")
         assert_match(self.process_manager.process_groups[1].forker, 'forker2', "Wrong forker selected")
+        assert_match(self.process_manager.forker_taskcounts['forker1'], 0, "Wrong count forker1")
+        assert_match(self.process_manager.forker_taskcounts['forker2'], 2, "Wrong count forker2")
 
     @patch.object(Cobalt.Proxy.DeferredProxyMethod, '__call__', return_value=1,
             side_effect=Cobalt.Exceptions.ComponentLookupError('failed lookup'))