Head "file has shrunk too much error" on /sys/ file

[Hadrien Lacour]

Hello,
I have this error going one:
        head -c -1 < 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
or
        head -c -1 
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

both procuce the "file has shrunk too much" error while doing nothing (the 
output
is the same as the file) but
        cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors | 
head -c -1

does work. I've copied the file to $HOME and everything works as it should, so 
the
location of the file may do something (/sys or /proc?). Any idea of why it 
doesn't work?