Avoid failing in symbolic links, search only for regular files

helpers/make-ubuntu-release-upgrader

@@ -260,7 +260,7 @@ chmod 755 DistUpgrade/trisquel-postinstall.sh
 
 replace changelogs.ubuntu.com packages.trisquel.info .
 
-/bin/sed -i 's/�~Lubuntu/�~Ltrisquel/g; s/被ubuntu/被trisquel/g; s#http://launchpad.net/ubuntu/+source/%s/%s/+changelog#http://trisquel.info/project/issues#g; s/<.*@ubuntu.com/<info@trisquel.info/g; s/ ubuntu\n/ trisquel\n/g; s/ubuntu\ /trisquel\ /g; s/\ ubuntu/\ trisquel/g; s/Ubuntu/Trisquel/g; s/ubuntu-desktop/trisquel-/g; s/www.ubuntu.com/trisquel.info/g; s/www.ubuntulinux.org/trisquel.info/g ' po/*.po $(find | grep py$) $(find | grep '\.glade$')
+/bin/sed -i 's/�~Lubuntu/�~Ltrisquel/g; s/被ubuntu/被trisquel/g; s#http://launchpad.net/ubuntu/+source/%s/%s/+changelog#http://trisquel.info/project/issues#g; s/<.*@ubuntu.com/<info@trisquel.info/g; s/ ubuntu\n/ trisquel\n/g; s/ubuntu\ /trisquel\ /g; s/\ ubuntu/\ trisquel/g; s/Ubuntu/Trisquel/g; s/ubuntu-desktop/trisquel-/g; s/www.ubuntu.com/trisquel.info/g; s/www.ubuntulinux.org/trisquel.info/g ' po/*.po $(find -type f | grep py$) $(find -type f | grep '\.glade$')
 
 rpl 11\.04 5\.0 DistUpgrade/*.ui
 rpl 11\.04 5\.0 po/* -R