pbuilder error "unmounting run/shm filesystem"

Attempting to use pbuilder to build a package on Ubuntu Trusty (v14.04) or Debian Jessie has been resulting in the follow error at the end of the attempted build:

I: unmounting run/shm filesystem
W: Could not unmount run/shm: umount: /run/shm: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
W: Retrying to unmount run/shm in 5s
umount: /run/shm: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
  Could not unmount run/shm, some programs might
  still be using files in /proc (klogd?).
  Please check and kill these processes manually
  so that I can unmount run/shm.  Last umount error was:
umount: /run/shm: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
  This error only affects chroots; you may want to use
  user-mode-linux to avoid this message.

Issue is in at least version 0.215, which is what both Trusty and Jessie currently have: reference Debian Bug number 709053 where this issue has been discussed, and where it is noted that adding USERUNSHM=no to the pbuilderrc resolves the issue.