slapgrid: Fix connectionless instance processing

Connection loss may result in `slap.exception.ConnectionError` being
raised during instance processing in addition to `RequestException`.

slapos/grid/slapgrid.py

@@ -59,6 +59,7 @@ from requests.exceptions import RequestException
 from lxml import etree
 
 from slapos import manager as slapmanager
+from slapos.slap.exception import ConnectionError
 from slapos.slap.slap import NotFoundError
 from slapos.slap.slap import ServerError
 from slapos.slap.slap import COMPUTER_PARTITION_REQUEST_LIST_TEMPLATE_FILENAME
@@ -1425,7 +1426,7 @@ stderr_logfile_backups=1
   def processComputerPartitionList(self):
     try:
       return self.processComputerPartitionListOnline()
-    except RequestException:
+    except (RequestException, ConnectionError):
       return self.processComputerPartitionListOffline()
 
   def processComputerPartitionListOnline(self):
@@ -1456,7 +1457,7 @@ stderr_logfile_backups=1
         self.processComputerPartition(computer_partition)
 
       # Handle connection loss at the next level
-      except RequestException:
+      except (RequestException, ConnectionError):
         raise
 
       # Send log before exiting

slapos/tests/test_slapgrid.py

@@ -308,7 +308,9 @@ class TestBasicSlapgridCP(BasicMixin, unittest.TestCase):
   def test_no_master(self):
     os.mkdir(self.software_root)
     os.mkdir(self.instance_root)
-    self.assertRaises(ConnectionError, self.grid.processComputerPartitionList)
+    self.assertEqual(
+      self.grid.processComputerPartitionList(),
+      slapgrid.SLAPGRID_OFFLINE_SUCCESS)
 
   def test_environment_variable_HOME(self):
     # When running instance, $HOME is set to the partition path