make sure that the UI is installed from an OSM repo

Signed-off-by: Jeremy Mordkoff <jeremy.mordkoff@gmail.com>
diff --git a/jenkins/UI/install b/jenkins/UI/install
index 45eb5ca..c145a53 100755
--- a/jenkins/UI/install
+++ b/jenkins/UI/install
@@ -101,6 +101,7 @@
 
 # now disable the RIFT OSM repo so that we'll get UI from
 # the OSM repos
+rm -f /etc/apt/sources.list.d/rift.list
 
 apt-get update
 apt-get install -y rw.ui-skyquake