clear disk.preserve when needed

also never set disk.wipe: setting preserve=False/ptable=gpt is
equivalent anyay.

subiquity/controllers/filesystem.py

@@ -397,6 +397,8 @@ class FilesystemController(BaseController):
             self.delete(subobj)
 
     def reformat(self, disk):
+        if disk.type == "disk":
+            disk.preserve = False
         self.clear(disk)
         for p in list(disk.partitions()):
             self.delete(p)
@@ -414,6 +416,10 @@ class FilesystemController(BaseController):
             self.create_filesystem(partition, spec)
             return
 
+        if len(disk.partitions()) == 0:
+            if disk.type == "disk":
+                disk.preserve = False
+
         needs_boot = self.model.needs_bootloader_partition()
         log.debug('model needs a bootloader partition? {}'.format(needs_boot))
         can_be_boot = DeviceAction.MAKE_BOOT in disk.supported_actions
@@ -534,4 +540,5 @@ class FilesystemController(BaseController):
                 part.wipe = 'zero'
                 self.model.grub_install_device = part
         else:
+            new_boot_disk.preserve = False
             self._create_boot_partition(new_boot_disk)

subiquity/models/filesystem.py

@@ -588,7 +588,7 @@ class Disk(_Device):
     serial = attr.ib(default=None)
     path = attr.ib(default=None)
     model = attr.ib(default=None)
-    wipe = attr.ib(default='superblock')
+    wipe = attr.ib(default=None)
     preserve = attr.ib(default=False)
     name = attr.ib(default="")
     grub_device = attr.ib(default=False)
@@ -1192,8 +1192,6 @@ class FilesystemModel(object):
         emitted_ids = set()
 
         def emit(obj):
-            if obj.type == 'disk' and not obj.used:
-                return
             r.append(asdict(obj))
             emitted_ids.add(obj.id)