Fixing build.

tests/travis/prepare.sh

 #!/bin/bash
 set -e
 
-travis_retry sudo apt-get update
+sudo apt-get update
 
 # Install XMLStarlet
-travis_retry sudo apt-get install -qq xmlstarlet
+sudo apt-get install -qq xmlstarlet
 
 # Install fonts for UI tests
 if [ "$TEST_SUITE" = "UITests" ];