Compose key suddenly permanently stopped working in emacs

[Christopher Barrington-Leigh]

Two days ago my compose key (Capslock), ie the key used to make accented characters, which works in all other applications including the terminal, suddenly stopped working inside Emacs. When I press it, I get "<Multi_key> is undefined" in the emacs status mini-buffer. Rebooting has not helped.

I'm using the latest 13.10 update, ie Emacs 23.4.1.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: emacs (not installed)
ProcVersionSignature: Ubuntu 3.11.0-15.23-generic 3.11.10
Uname: Linux 3.11.0-15-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
Date: Thu Jan 30 18:12:17 2014
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-12-13 (48 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
SourcePackage: emacs-defaults
UpgradeStatus: No upgrade log present (probably fresh install)

[Christopher Barrington-Leigh (cpbl)]

This has now happened in 14.04 as well.

Emacs still works fine if I run it as

env XMODIFIERS="@im=none" emacs

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[mmassyn (markwmassyn)]

Compose key works again with

env -u XMODIFIERS emacs

[Christopher Barrington-Leigh (cpbl)]

Yes, I agree that the following are both effective:

env -u XMODIFIERS emacs
env XMODIFIERS="@im=none" emacs

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