Changed APT test.

tests/test_apt.sh

@@ -16,7 +16,9 @@ if ( dpkg -s sl >/dev/null 2>&1 ); then
 fi 
 
 # Installation testing package sl
-apt-get update && apt-get install -y sl && apt-get remove -y sl
+apt-get update
+apt-get install -y sl
+apt-get remove -y sl
 
 if [ ! -f /etc/apt/apt.conf.d/20auto-upgrades ]; then
     if [ ! -f /etc/apt/apt.conf.d/50unattended-upgrades ]; then