storage/kernels: fix listing volumes

Pool.volumes property is implemented in a base class, individual drivers
should provide list_volumes() method as a backend for that property.
Fix this in a LinuxKernel pool.

qubes/storage/kernels.py

@@ -209,8 +209,7 @@ class LinuxKernel(Pool):
             [pool for pool in app.pools.values() if pool is not self],
             self.dir_path)
 
-    @property
-    def volumes(self):
+    def list_volumes(self):
         ''' Return all known kernel volumes '''
         return [LinuxModules(self.dir_path,
                              kernel_version,

qubes/tests/storage_kernels.py

@@ -250,7 +250,7 @@ class TC_03_KernelPool(qubes.tests.QubesTestCase):
 
     def test_002_pool_volumes(self):
         """ List volumes """
-        volumes = self.app.pools[self.POOL_NAME].volumes
+        volumes = list(self.app.pools[self.POOL_NAME].volumes)
         self.assertEqual(len(volumes), 1)
         vol = volumes[0]
         self.assertEqual(vol.vid, 'dummy')