For this example, I had a collection of text files with embedded mode lines to setup the mode for org-mode. I wanted to do away with the mode line and rename them from txt files to org files.
Build the GLOB before hand and verify with ls. For example ls *.txt would have the GLOB value in the example replaced with *.txt.
The git mv renames the files.
for i in $(find . -iname "GLOB"); do
git mv "$i" "$(echo $i | rev | cut -d '.' -f 2- | rev).org";
done