Merge lp:~twom/loggerhead/anootate-changes-should-exist into lp:loggerhead

[Tom Wardill]

Check changes exist before using them.
Based on patch by lp:~pnutzh4x0r

Changes may not exist in the case of 'ghost revisions', but we assume they do. Check that any changes are retrieved and if not, create an object so we can at least render the page.

Based on the patch provided by lp:~pnutzh4x0r in LP: #376586

[Colin Watson (cjwatson)]

review: Approve

=== modified file 'loggerhead/controllers/annotate_ui.py'
--- loggerhead/controllers/annotate_ui.py	2020-06-04 20:30:54 +0000
+++ loggerhead/controllers/annotate_ui.py	2020-07-14 16:45:11 +0000
@@ -16,6 +16,7 @@
 # Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335  USA
 #
 
+from datetime import datetime
 import itertools
 
 from ..controllers.view_ui import ViewUI
@@ -48,7 +49,12 @@
 
                 change = change_cache.get(line_revid, None)
                 if change is None:
-                    change = self._history.get_changes([line_revid])[0]
+                    changes = self._history.get_changes([line_revid])
+                    if changes:
+                        change = changes[0]
+                    else:
+                        change = util.Container(
+                            authors='', date=datetime.now(), revno='')
                     change_cache[line_revid] = change
 
                 try: