git-gui: fix multi selected file operation
-rwxr-xr-x 1813 GIT-VERSION-GEN
-rw-r--r-- 11667 Makefile
-rwxr-xr-x 1372 git-gui--askpass
-rwxr-xr-x 96932 git-gui.sh
drwxr-xr-x - lib
drwxr-xr-x - macosx
drwxr-xr-x - po
drwxr-xr-x - windows