Corrected some mistakes:

 - Use sed, not sedhelper, add -i for inline editing
 - added /ubuntu to the url to replace

helpers/make-pbuilder

-#!/bin/bash
-#
-#    Copyright (C) 2016  Kevin Peng <kkpengboy@gmail.com>
-#
-#    This program is free software; you can redistribute it and/or modify
-#    it under the terms of the GNU General Public License as published by
-#    the Free Software Foundation; either version 3 of the License, or
-#    (at your option) any later version.
-#
-#    This program is distributed in the hope that it will be useful,
-#    but WITHOUT ANY WARRANTY; without even the implied warranty of
-#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#    GNU General Public License for more details.
-#
-#    You should have received a copy of the GNU General Public License
-#    along with this program; if not, write to the Free Software
-#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
-#
-
-VERSION=1
-
-. ./config
-
-sedhelper debian/rules 's/archive\.ubuntu\.com/archive\.trisquel\.info/g'
-sedhelper debian/rules "s/$UPSTREAM/$CODENAME/g"
-
-changelog "Rebrand for Trisquel"
-compile
-
+#!/bin/bash
+#
+#    Copyright (C) 2016  Kevin Peng <kkpengboy@gmail.com>
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program; if not, write to the Free Software
+#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+#
+
+VERSION=1
+
+. ./config
+
+sed "s/archive\.ubuntu\.com\/ubuntu/archive\.trisquel\.info\/trisquel/g" -i debian/rules
+sed "s/$UPSTREAM/$CODENAME/g" -i debian/rules
+
+changelog "Rebrand for Trisquel"
+compile
\ No newline at end of file