grub-mkconfig (running as update-grub) gives scary message "grep: input file '/tmp/grub.cfg.new' is also the output"

Similar bug 915008

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

Fixed in bzr.

This bug was fixed in the package grub2 - 1.99-16ubuntu1

---------------
grub2 (1.99-16ubuntu1) precise; urgency=low

  * Resynchronise with Debian. Remaining changes:
    - Adjust for default Ubuntu boot options ("quiet splash").
    - Default to hiding the menu; holding down Shift at boot will show it.
    - Set a monochromatic theme and an appropriate background for Ubuntu.
    - Apply Ubuntu GRUB Legacy changes to legacy update-grub script.
    - Fix backslash-escaping in merge_debconf_into_conf.
    - Remove "GNU/Linux" from default distributor string.
    - Add crashkernel option.
    - Bypass menu unless other OSes are installed or Shift is pressed.
    - Allow Shift to interrupt 'sleep --interruptible'.
    - Reduce visual clutter in normal mode.
    - Remove verbose messages printed before reading configuration.
    - Suppress kernel/initrd progress messages, except in recovery mode.
    - Show the boot menu if the previous boot failed.
    - Don't generate device.map during grub-install or grub-mkconfig.
    - Adjust upgrade version checks for Ubuntu.
    - Suppress "GRUB loading" message unless Shift is held down.
    - Adjust versions of grub-doc and grub-legacy-doc conflicts.
    - Fix LVM/RAID probing in the absence of /boot/grub/device.map.
    - Look for .mo files in /usr/share/locale-langpack first.
    - Build-depend on qemu-kvm rather than qemu-system for grub-pc tests.
    - Check hardware support before using gfxpayload=keep.
    - Put second and subsequent Linux menu entries in a submenu.
    - Preferred resolution detection for VBE.
    - Set vt.handoff=7 for smooth handoff to kernel graphical mode.
    - Update default/grub.md5sum to include maverick's default md5sum.
    - In recovery mode, add nomodeset to the Linux kernel arguments, and
      remove the 'set gfxpayload=keep' command.
    - Skip Windows os-prober entries on Wubi systems, and suppress the menu
      by default if those are the only other-OS entries.
    - Handle probing striped DM-RAID devices.
    - Replace 'single' by 'recovery' when friendly-recovery is installed.
  * Use qemu -no-kvm in tests for now to work around LP #947597.
  * Disable cursor as early as possible in grub_main (LP: #861048).

grub2 (1.99-16) unstable; urgency=low

  * Backport from upstream:
    - Build with -fno-asynchronous-unwind-tables to save space (closes:
      #662787).

grub2 (1.99-15) unstable; urgency=low

  [ Adam Conrad ]
  * grub.cfg_400.patch: Redirect grep stdout to /dev/null since
    grub-mkconfig is "exec > grub.cfg.new", which causes grep's input
    and output to be the same FD (LP: #934269) (closes: #652972)
  * efi_disk_cache.patch: Bump the disk cache on EFI systems to
    dramatically reduce load times for vmlinux/initrd (LP: #944347)

  [ Colin Watson ]
  * no_libzfs.patch: Use xasprintf rather than asprintf.
  * Backport from upstream:
    - Rewrite XFS btree parsing; fixes invalid BMAP (closes: #657776).
    - Handle newer autotools, and add some missing quotes in the process.
      (Note that this moves grub-mkconfig_lib and update-grub_lib to
      /usr/share/grub; I added links in /usr/lib/grub for compatibility.)
    - Fix incorrect identifiers ...