General protection against tracebacks during populate.

The goal here is to absolutely minimize tracebacks that occur when
populating the devicetree. There are mechanisms in place that will limit
the supported functionality for managing such devices, but there will be
no tracebacks until/unless the user tries to manage them in ways that
are precluded by the detection issues previously encountered.

blivet/populator/populator.py

@@ -37,6 +37,7 @@
 from ..devices import MDRaidArrayDevice
 from ..devices import MultipathDevice
 from ..devices import NoDevice
+from ..devices import StorageDevice
 from ..devicelibs import disk as disklib
 from ..devicelibs import lvm
 from .. import formats
@@ -262,7 +263,19 @@ def handle_device(self, info, update_orig_fmt=False):
             helper_class = self._get_device_helper(info)
 
         if helper_class is not None:
-            device = helper_class(self, info).run()
+            try:
+                device = helper_class(self, info).run()
+            except DeviceTreeError as e:
+                log.error("error handling device %s: %s", name, str(e))
+                device = self.get_device_by_name(name, incomplete=True, hidden=True)
+                if device is None:
+                    try:
+                        parents = self._add_slave_devices(info)
+                    except DeviceTreeError:
+                        parents = []
+
+                    device = StorageDevice(name, parents=parents, uuid=udev.device_get_uuid(info),
+                                           exists=True)
 
         if not device:
             log.debug("no device obtained for %s", name)
@@ -302,7 +315,10 @@ def handle_format(self, info, device):
 
         helper_class = self._get_format_helper(info, device=device)
         if helper_class is not None:
-            helper_class(self, info, device).run()
+            try:
+                helper_class(self, info, device).run()
+            except DeviceTreeError as e:
+                log.error("error handling formatting on %s: %s", device.name, str(e))
 
         log.info("got format: %s", device.format)