CrOS: Replace broken slaves on ChromiumOS.

masters/master.chromiumos/slaves.cfg

Index: masters/master.chromiumos/slaves.cfg
diff --git a/masters/master.chromiumos/slaves.cfg b/masters/master.chromiumos/slaves.cfg
index 733b184529643409ff09ef29ec5fdc1a2250bab0..a8d690a8a14696eefbb32fbf371db1c3ba629f9b 100644
--- a/masters/master.chromiumos/slaves.cfg
+++ b/masters/master.chromiumos/slaves.cfg
@@ -15,10 +15,12 @@ def shared(slave_type):
   return '%s_shared' % (slave_type,)
 
 # Baremetal slaves
-sa.AddPool(SlaveType.BAREMETAL, *('build%s-m2' % (n,) for n in (
+sa.AddPool(SlaveType.BAREMETAL, *('build%s-m2' % (n,) for n in set([
     85, 86, 87, 91, 92, 93, 112, 118, 141, 162, 174, 182,
     203, 263, 323, 326, 327
-)))
+]) - set([
+  91, # crbug.com/600599
+])))
 
 # GCE slaves
 sa.AddPool(SlaveType.GCE, *('cros%s-c2' % (n,) for n in (