ssh disconnect escape sequence doesn't work on a broken multiplexed connection

I use the following SSH configuration options:
  ControlMaster auto
  ControlPath ~/.ssh/.socket-%r@%h:%p
  ControlPersist 60

It looks as if it's configured correctly because opening multiple connections using the same username and host-port combination shares the first connection.

[Enter], [~], [.] closes each session individually, which is great. However, that disconnect escape sequence appears to do absolutely nothing if the multiplexed connection dies abnormally (for instance, if my WiFi connection dies), which is the time when I most need the disconnect sequence to work, since I'm not going to be doing much on that dead session anymore, and I'd like to restart it.

[Enter], [~], [.] works fine on a *nonmultiplexed* connection when it dies abnormally.

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$ lsb_release -rd
Description: Ubuntu 13.04
Release: 13.04

$ apt-cache policy openssh-client
openssh-client:
  Installed: 1:6.1p1-4
  Candidate: 1:6.1p1-4
  Version table:
 *** 1:6.1p1-4 0
        500 http://us.archive.ubuntu.com/ubuntu/ raring/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: openssh-client 1:6.1p1-4
ProcVersionSignature: Ubuntu 3.8.0-23.34-generic 3.8.11
Uname: Linux 3.8.0-23-generic x86_64
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
Date: Sat Jun 22 09:01:57 2013
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-04-04 (78 days ago)
InstallationMedia: Lubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.1)
MarkForUpload: True
RelatedPackageVersions:
 ssh-askpass N/A
 libpam-ssh N/A
 keychain N/A
 ssh-askpass-gnome N/A
SSHClientVersion: OpenSSH_6.1p1 Debian-4, OpenSSL 1.0.1c 10 May 2012
SourcePackage: openssh
UpgradeStatus: Upgraded to raring on 2013-05-25 (27 days ago)