Fix numeric natural keys resolving to the wrong asset on import

tests/test_csv_import.py

@@ -335,3 +335,29 @@ def test_reconcile_still_binds_normalized_exact(db):
     _db.session.rollback()
 
 
+
+
+def test_a_numeric_assetnumber_is_read_as_a_name_not_an_id(db):
+    """This site numbers operations 0NNN, so numeric natural keys are real.
+
+    An all-digit string used to be taken at face value as an id. `0600` became
+    id 600 - a different asset, or none - which is how an Azure device import
+    died on a foreign key partway through, and how a PC could instead have been
+    bound silently to a printer's record. The label wins when one matches.
+    """
+    resolver = Resolver()
+    seed_reference(resolver)
+    import_csv('assets', 'assetnumber,assettypeid\n0600,Machine\n',
+               resolver=resolver, commit=True)
+    realid = _db.session.execute(_db.text(
+        "select assetid from assets where assetnumber = '0600'")).scalar()
+
+    # Force the ambiguity: an id that is NOT the one named 0600.
+    assert resolver.resolve('assets', 'assetid', '0600') == realid
+
+
+def test_a_number_naming_nothing_is_still_read_as_an_id(db):
+    """Round-tripped exports and sites that know their ids keep working."""
+    resolver = Resolver()
+    seed_reference(resolver)
+    assert resolver.resolve('assets', 'assetid', '999999') == 999999