Mercurial Keyring Fails Authentication

I recently upgraded to Ubuntu 16.04 from 14.04, 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 (since it was mentioned in the error), 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. I tried asking in the support channels, but they asked me to file a bug instead... https://answers.launchpad.net/ubuntu/+question/288642

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: python-keyring 7.3-1
ProcVersionSignature: Ubuntu 4.4.0-7.22-generic 4.4.2
Uname: Linux 4.4.0-7-generic x86_64
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
Date: Tue Mar 15 13:22:41 2016
InstallationDate: Installed on 2016-03-02 (13 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160224)
PackageArchitecture: all
SourcePackage: python-keyring
UpgradeStatus: No upgrade log present (probably fresh install)