Devices: saving port 22 overrides a port inherited from a later Host entry (review round 25)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_devices.py

@@ -130,6 +130,10 @@ class Migration(Base):
         self.reg.sync_from_config(seed=False)
         self.assertEqual(self.reg.by_alias("frame")["port"], 2222)  # what ssh itself would use
         self.assertEqual(self.reg.by_alias("frame-2")["port"], 2222)  # its own Port line
+        # Saving 22 must then say so in the block, or ssh would go on inheriting 2222.
+        self.assertTrue(fd.rewrite_block("frame", port=22))
+        self.assertEqual(fd.effective_port("frame", self.ssh / "config"), 22)
+        self.assertFalse(fd.rewrite_block("frame", port=22))  # and only once
 
     def test_setup_finding_a_new_address_adds_it(self):
         self.reg.sync_from_config(seed=False)