TypeError: Can't instantiate abstract class Changeset with abstract methods get_changes

[Andras Korn]

When running dbfts index, I get:

Indexed 225 objects from wiki
Indexed 4933 objects from ticket
Indexed 2 objects from milestone
TypeError: Can't instantiate abstract class Changeset with abstract methods get_changes

The trac log says

2021-03-30 17:14:06,977 Trac[console] ERROR: Exception in trac-admin command: u'dbfts index'
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/trac/admin/console.py", line 112, in onecmd
    rv = cmd.Cmd.onecmd(self, line) or 0
  File "/usr/lib/python2.7/cmd.py", line 220, in onecmd
    return self.default(line)
  File "/usr/lib/python2.7/dist-packages/trac/admin/console.py", line 291, in default
    return self.cmd_mgr.execute_command(*args)
  File "/usr/lib/python2.7/dist-packages/trac/admin/api.py", line 127, in execute_command
    return f(*fargs)
  File "/usr/lib/python2.7/dist-packages/tracdbfts/admin.py", line 71, in _do_index
    for n, item in enumerate(iter_(), 1):
  File "/usr/lib/python2.7/dist-packages/tracdbfts/admin.py", line 144, in _iter_changesets
    for cset in iter_csets(repos):
  File "/usr/lib/python2.7/dist-packages/tracdbfts/admin.py", line 160, in _iter_cached_csets
    from_utimestamp(date))
TypeError: Can't instantiate abstract class Changeset with abstract methods get_changes

This is with Trac 1.2.2.

[Jun Omae]

In 18117:

TracDbftsPlugin: fix unable to instantiate abstract Changeset class since Trac 1.2 (closes #13989)