fix(instances): Refresh ISO list says which pools it could not read

A pool whose refresh failed, one busy with a volume copy for example,
was skipped without a word, so a hand-copied image stayed missing with
no reason given. The other pools are still refreshed; each failure is
shown with libvirt's error.

The API comment no longer says listing the ISO images refreshes pools.

vrtManager/instance.py

@@ -1715,10 +1715,15 @@ class wvmInstance(wvmConnect):
 
     def refresh_iso_pools(self):
         """Refresh the active pools, so that an image copied to one by hand
-        is listed by get_iso_media."""
+        is listed by get_iso_media. A pool that fails does not stop the
+        others; returns the errors, by pool name."""
+        failed = {}
         for pool in self.wvm.listAllStoragePools(VIR_CONNECT_LIST_STORAGE_POOLS_ACTIVE):
-            with contextlib.suppress(libvirtError):  # stopped or removed meanwhile
+            try:
                 pool.refresh(0)
+            except libvirtError as err:
+                failed[pool.name()] = err
+        return failed
 
     def get_iso_media(self):
         """The .iso volumes libvirt knows in the active pools; one copied in

vrtManager/tests/test_iso_media.py

@@ -91,13 +91,21 @@ class IsoListTestCase(unittest.TestCase):
         self.assertEqual(inst.get_iso_media(), ["b.iso"])
 
     def test_refresh_reads_every_active_pool_again(self):
-        a, b = pool([], refresh_error=True), pool([])
+        a, b = pool([]), pool([])
         inst = self.wvm(a, b)
-        inst.refresh_iso_pools()
+        self.assertEqual(inst.refresh_iso_pools(), {})
         inst.wvm.listAllStoragePools.assert_called_once_with(VIR_CONNECT_LIST_STORAGE_POOLS_ACTIVE)
         a.refresh.assert_called_once_with(0)
         b.refresh.assert_called_once_with(0)
 
+    def test_a_failed_refresh_is_returned_and_the_others_still_run(self):
+        a, b = pool([], refresh_error=True), pool([])
+        a.name.return_value = "busy"
+        failed = self.wvm(a, b).refresh_iso_pools()
+        self.assertEqual(list(failed), ["busy"])
+        self.assertIsInstance(failed["busy"], libvirtError)
+        b.refresh.assert_called_once_with(0)
+
 
 if __name__ == "__main__":
     unittest.main()