fixup: ostreeartifactcache: Change some exception stuff

1 files changed, 7 insertions, 2 deletions

diff --git a/morphlib/ostreeartifactcache.py b/morphlib/ostreeartifactcache.py
index ed060e59..f0fd6b56 100644
--- a/morphlib/ostreeartifactcache.py
+++ b/morphlib/ostreeartifactcache.py
@@ -29,6 +29,12 @@ import morphlib
 from morphlib.artifactcachereference import ArtifactCacheReference
 
 
+class NotCachedError(morphlib.Error):
+
+    def __init__(self, ref):
+        self.msg = 'Failed to checkout %s from the artifact cache.' % ref
+
+
 class OSTreeArtifactCache(object):
     """Class to provide the artifact cache API using an OSTree repo."""
 
@@ -165,8 +171,7 @@ class OSTreeArtifactCache(object):
             self.repo.touch_ref(ref)
         except GLib.GError as e:
             logging.debug('OSTree raised an exception: %s' % e)
-            raise cliapp.AppException('Failed to checkout %s from artifact '
-                                      'cache.' % ref)
+            raise NotCachedError(ref)
         return directory
 
     def list_contents(self):