Move common libs to libs/common

libs/common/stevedore/exception.py

@@ -0,0 +1,23 @@
+#  Licensed under the Apache License, Version 2.0 (the "License"); you may
+#  not use this file except in compliance with the License. You may obtain
+#  a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#  License for the specific language governing permissions and limitations
+#  under the License.
+
+
+class NoUniqueMatch(RuntimeError):
+    """There was more than one extension, or none, that matched the query."""
+
+
+class NoMatches(NoUniqueMatch):
+    """There were no extensions with the driver name found."""
+
+
+class MultipleMatches(NoUniqueMatch):
+    """There were multiple matches for the given name."""