Mercurial Keyring Fails Authentication

I recently upgraded to Ubuntu 16.04, and while pretty much everything works as expected, I can no longer push to my remote Mercurial repository. Here is the error:

 ~/drafts $ hg push
pushing to https://hg.csswg.org/drafts/
searching for changes
ERROR:dbus.proxies:Introspect error on :1.173:/modules/kwalletd: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying
http authorization required
realm: css-drafts
user: fantasai (fixed in .hg/hgrc)
Password:

In the past, there wouldn't be a password prompt here, there would be a keyring window asking me for my local password, and then it would just work for the rest of my X session. At the moment, none of the passwords I can think of as being remotely relevant seem to work, and the entire thing crashes after I press enter.

Fwiw, I did try installing kwalletd, but that didn't help. Running it on the commend line gave the following error:
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
kwalletd(24651): Communication problem with "kwalletd" , it probably crashed.
Error message was: "org.freedesktop.DBus.Error.NoReply" : " "Message recipient disconnected from message bus without replying"

Fwiw, the Python keyring configuration file
  https://pypi.python.org/pypi/keyring#config-file-path
appears not to exist:
$ python -c "import keyring.util.platform_; print(keyring.util.platform_.config_root())"
/home/fantasai/.local/share/python_keyring
$ ls /home/fantasai/.local/share/python_keyring
ls: cannot access '/home/fantasai/.local/share/python_keyring': No such file or directory

Don't really know where to go from here.