Create a .GIF of all versions of a .PNG from Git

example.sh

mkdir ~/os
git log openstatesmap.png | grep commit | awk '{print $2}' | tac > ~/allfifty.rev
I=0; while read foo; do git reset $foo --hard; cp openstatesmap.png ~/os/$I.png; let I=$I+1; done < ~/allfifty.rev
convert -dispose previous -delay 20 -loop 0 `ls *.png | sort -n` openstates.gif