Created attachment 704827 [details]
dmesg from the system with the problem

Description of problem:
Grub edit fails when passing long line.

Version-Release number of selected component (if applicable):


How reproducible:
every time that the line is passed in editing.  Editing is okay if careful never to go past it and back onto it.  

Steps to Reproduce:
1. start boot
2. press e to edit
3. go down to the line with the kernel boot parameters
4a. go past the line then try to step back left to the end of it
4b. go to the end of the line, step back; press enter then delete
5. try to edit / try to save / try to boot
  
Actual results:
editor locks up in varied ways;  sometimes cursor movement is possible but no character insertion.  Sometimes nothing at all is possible.  Mostly boot with F10 doesn't do anything

Expected results:
grub continues to work normally and allows editing 

Additional info:
None of the other grub edit bugs such as Bug #866275 or Bug #859632 seem to be the same thing.  

menu entry where editing problems occur looks like this (UUIDs converted to xxxx)

menuentry 'Fedora (3.7.9-201.fc18.x86_64)' --class fedora --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-xxxx' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod ext2
        set root='hd0,msdos2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2'  xxxx
        else
          search --no-floppy --fs-uuid --set=root xxxx
        fi
        echo 'Loading Fedora (3.7.9-201.fc18.x86_64)'
        linux   /vmlinuz-3.7.9-201.fc18.x86_64 root=/dev/mapper/vg_main-lv_fedora_2013_02_03 ro rd.lvm.lv=vg_main/lv_swap rd.md=0 rd.dm=0 SYSFONT=True rd.luks.uuid=luks-xxxx  KEYTABLE=us rd.lvm.lv=vg_aga_main/lv_fedora_2013_02_03 LANG=en_US.UTF-8 rhgb quiet reboot=pci
        echo 'Loading initial ramdisk ...'
        initrd /initramfs-3.7.9-201.fc18.x86_64.img
}