children: don't pass filectx to displayer
displayer doesn't want a fctx but a ctx. It failed with -Tdefault template.
Traceback (most recent call last):
...
File "mercurial/templatekw.py", line 212, in showbookmarks
bookmarks = args['ctx'].bookmarks()
AttributeError: 'filectx' object has no attribute 'bookmarks'