Never file a part marker under its own PC

plugins/computers/plugin.py

@@ -798,19 +798,26 @@ class ComputersPlugin(BasePlugin):
                 rel.isactive = False
 
         operation = self._link_marker_to_operation(
-            markerasset, machinenumber, warnings)
+            markerasset, machinenumber, pcasset, warnings)
 
         return [{'assetid': markerasset.assetid,
                  'assetnumber': markerasset.assetnumber,
                  'operationassetid': operation}]
 
-    def _link_marker_to_operation(self, markerasset, machinenumber, warnings):
+    def _link_marker_to_operation(self, markerasset, machinenumber, pcasset,
+                                  warnings):
         """Make a marker `partof` the operation whose number its PC reports.
 
         Unlike the PC-to-machine link this does NOT contest: an operation can
         hold any number of markers, which is the whole point. Moving a marker to
         another operation archives the old membership rather than deleting it,
         so where a marker used to live stays answerable.
+
+        Refuses to file a marker under the reporting PC. A PC first seen before
+        the machine-number fix was created with the machine number as its OWN
+        asset number, and that is deliberately never overwritten, so looking up
+        the number can return the PC itself. Filing the marker partof its own PC
+        would read, on the machine page, as the PC being the operation.
         """
         from shopdb.api import AssetRelationship, RelationshipType, Asset
 
@@ -834,6 +841,13 @@ class ComputersPlugin(BasePlugin):
             return None
         if operation.assetid == markerasset.assetid:
             return None
+        if pcasset is not None and operation.assetid == pcasset.assetid:
+            warnings.append(
+                'machine number {!r} is this PC\'s own asset number; marker '
+                'not filed under an operation. Rename the PC asset to its '
+                'hostname, or create the operation asset.'.format(
+                    machinenumber))
+            return None
 
         links = AssetRelationship.query.filter(
             AssetRelationship.sourceassetid == markerasset.assetid,