completion: add space after completed filename

Just like before fea16b4 (git-completion.bash: add support for path
completion).

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -255,7 +255,7 @@ __gitcomp_file ()
 	__gitcompadd "$1" "${2-}" "${3-$cur}" ""
 
 	# use a hack to enable file mode in bash < 4
-	compopt -o filenames 2>/dev/null ||
+	compopt -o filenames +o nospace 2>/dev/null ||
 	compgen -f /non-existing-dir/ > /dev/null
 }