make git-svn-externals-update more usable

Author: rcc

git-svn-externals-update

@@ -1,11 +1,15 @@
 #!/bin/bash
 
-for dir in *; do
+toplevel_directory="$(git rev-parse --show-cdup)"
+[ -n "$toplevel_directory" ] && { echo "please run from the toplevel directory"; exit 1; }
+
+find .git_externals -type d -name .git | while read gitdir; do
+	dir=$(dirname "$gitdir")
     if [ -d $dir ]; then
-	cd $dir
+	pushd $dir
 	echo $dir
 	git svn fetch
 	git svn rebase
-	cd ..
+	popd
     fi
-done
+done