I can confirm this bug on Fedora 22 (Linux).
$ lsb_release -d
Description: Fedora release 22 (Twenty Two)
The output from free on this machine is:
$ free
total used free shared buff/cache available
Mem: 8093376 4613684 222132 291592 3257560 2885712
Swap: 0 0 0
And that is not the expected format:
I think the problem is line 4183:
4173: sub memfreescript {
4174: # Returns:
4175: # shellscript for giving available memory in bytes
4176: if(not $script) {
4177: my %script_of = (
4178: # $ free
4179: # total used free shared buffers cached
4180: # Mem: 8075152 4922780 3152372 338856 233356 1658604
4181: # -/+ buffers/cache: 3030820 5044332
4182: # Swap: 8286204 116924 8169280
4183: "linux" => q{ print (1024*((grep /buffers.cache/, `free`)[0] =~ /buffers.cache:\s+\S+\s+(\S+)/)[0]) },
Regards
Martin M. S. Pedersen