fix the way we handle deleted notes

The aggregated change information for a deleted note includes the SHA as
well as the filename. Extract both from the tuple separately so the path
value is set correctly to a filename.

Change-Id: I41fb4a7a0f6d24af47c8f059945b9bf45f859f15
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

releasenotes/notes/fix-delete-handling-55232c50b647aa57.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Correct a problem with handling deleted release notes that
+    triggered a TypeError with a message like "Can't mix strings and
+    bytes in path components"

reno/scanner.py

@@ -176,7 +176,7 @@ class _ChangeAggregator(object):
                     path = c.old.path.decode('utf-8') if c.old.path else None
                     if _note_file(path):
                         uid = _get_unique_id(path)
-                        by_uid[uid].append((c.type, path))
+                        by_uid[uid].append((c.type, path, sha))
                     else:
                         LOG.debug('ignoring')
                 elif c.type == diff_tree.CHANGE_MODIFY:
@@ -1013,7 +1013,7 @@ class Scanner(object):
                     tracker.add(fullpath, sha, current_version)
 
                 elif c_type == diff_tree.CHANGE_DELETE:
-                    path = change[-1]
+                    path, blob_sha = change[-2:]
                     fullpath = os.path.join(notesdir, path)
                     tracker.delete(fullpath, sha, current_version)
 

reno/tests/test_scanner.py

@@ -1883,7 +1883,7 @@ class AggregateChangesTest(Base):
         ]
         results = list(self.aggregator.aggregate_changes(entry, changes))
         self.assertEqual(
-            [('%016x' % n, 'delete', name)],
+            [('%016x' % n, 'delete', name, entry.commit.id)],
             results,
         )