rebase: preserve active bookmark when not at head (issue3813)

Now that the working directory parent is preserved, we can preserve the active
bookmark too.

hgext/rebase.py

@@ -382,7 +382,7 @@ def rebase(ui, repo, **opts):
             ui.note(_("%d revisions have been skipped\n") % len(skipped))
 
         if (activebookmark and
-            repo['tip'].node() == repo._bookmarks[activebookmark]):
+            repo['.'].node() == repo._bookmarks[activebookmark]):
                 bookmarks.setcurrent(repo, activebookmark)
 
     finally:

tests/test-rebase-bookmarks.t

@@ -127,6 +127,12 @@ Keep active bookmark on the correct changeset
   |
   o  0: 'A' bookmarks:
   
+  $ hg bookmarks
+     W                         1:41acb9dca9eb
+   * X                         2:e926fccfa8ec
+     Y                         3:3d5fa227f4b5
+     Z                         3:3d5fa227f4b5
+
 rebase --continue with bookmarks present (issue3802)
 
   $ hg up 2