Bug#752394: cups installation hangs in triggers

[Vincent Lefevre <vincent@vinc17.net>]

Package: cups
Version: 1.7.3-3
Severity: grave
Justification: renders package unusable

During an upgrade, I got:

[...]
Processing triggers for cups (1.7.3-3) ...

Then, nothing for 3 minutes. A ps output showed:

UID        PID  PPID  C STIME TTY          TIME CMD
root     20661 20645  0 13:03 pts/1    00:00:00 lpstat -h /var/run/cups/cups.sock -r

(thus started 3 minutes ago). I couldn't kill it from the terminal
with Ctrl-C or Ctrl-\. I had to start another terminal and do a
kill -9 on it.

-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.14-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=POSIX, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages cups depends on:
ii  cups-client            1.7.3-3
ii  cups-common            1.7.3-3
ii  cups-core-drivers      1.7.3-3
ii  cups-daemon            1.7.3-3
ii  cups-filters           1.0.54-2
ii  cups-ppdc              1.7.3-3
ii  cups-server-common     1.7.3-3
ii  debconf [debconf-2.0]  1.5.53
ii  ghostscript            9.05~dfsg-8.1
ii  libavahi-client3       0.6.31-4
ii  libavahi-common3       0.6.31-4
ii  libc-bin               2.19-3
ii  libc6                  2.19-3
ii  libcups2               1.7.3-3
ii  libcupscgi1            1.7.3-3
ii  libcupsimage2          1.7.3-3
ii  libcupsmime1           1.7.3-3
ii  libcupsppdc1           1.7.3-3
ii  libgcc1                1:4.9.0-7
ii  libstdc++6             4.9.0-7
ii  libusb-1.0-0           2:1.0.19-1
ii  lsb-base               4.1+Debian13
ii  poppler-utils          0.24.5-4
ii  procps                 1:3.3.9-5

Versions of packages cups recommends:
ii  avahi-daemon                     0.6.31-4
ii  colord                           1.2.1-1
ii  cups-filters [ghostscript-cups]  1.0.54-2
ii  printer-driver-gutenprint        5.2.10-2

Versions of packages cups suggests:
ii  cups-bsd               1.7.3-3
pn  cups-pdf               <none>
ii  foomatic-db            20140325-1
ii  hplip                  3.14.6-1
ii  printer-driver-hpcups  3.14.6-1
pn  smbclient              <none>
ii  udev                   204-10

-- debconf information:
  cupsys/backend: lpd, socket, usb, snmp, dnssd
  cupsys/raw-print: true