Adjust the quilt/setup script to do the equivalent of the GNU file -b option

This patch will be passed upstream

--- quilt/setup.in.orig 2015-02-16 16:11:48.761425804 -0800

+++ quilt/setup.in 2015-02-16 16:13:14.101523600 -0800

@@ -162,7 +162,7 @@

filetype="xz"

;;

*)

- filetype=$(file -b "$file")

+ filetype=$(file "$file" | sed 's/^.*:[\t ]*//')

;;

esac

@@ -389,7 +389,7 @@

"# Source: "*)

shift 2

source="$@"

- filetype=$(file -b "$source")

+ filetype=$(file "$source" | sed 's/^.*:[\t ]*//')

case "$filetype" in

Zip*)

echo "unzip ${tar_dir:-.} ${source// /\\ }"