Enforce git commands being run inside git folder

Author: Stunkymonkey

bin/git-authors.sh

@@ -1,10 +1,12 @@
 #!/bin/sh
 
+# Enforce being in a git repository
+git rev-parse --is-inside-work-tree >/dev/null || exit $?
+
 # save as i.e.: git-authors and set the executable flag
 git ls-tree -r -z --name-only HEAD -- "${1}" \
   | xargs -0 -n1 git blame --line-porcelain HEAD \
   | grep  "^author " \
   | sort \
   | uniq -c \
   | sort -nr
-