Disable service autostart on package install

Debian and its derivatives will autostart services when installing
packages. However, often we need to configure installed software
before it is ready to run, so it's preferable to use Salt states and
requisites to handle package installation or upgrades, configuration
changes and service [re]starting.

Adding a policy-rc.d file with exit code 101 sets a policy which denies
this default behavior. Making this change in the install script also
prevents new builders from attempting to contact the Salt master before
they have been configured properly.

.travis/install_salt

@@ -8,6 +8,8 @@ install_salt () {
     if [ "${OS_NAME}" = "linux" ]; then
         printf "$0: installing salt for Linux\n"
         # Use Trusty (Ubuntu 14.04) on Travis
+        # Don't autostart services
+        printf '#!/bin/sh\nexit 101\n' | sudo install -m 755 /dev/stdin /usr/sbin/policy-rc.d
         curl https://repo.saltstack.com/apt/ubuntu/14.04/amd64/archive/2015.5.8/SALTSTACK-GPG-KEY.pub | sudo apt-key add -
         printf 'deb http://repo.saltstack.com/apt/ubuntu/14.04/amd64/archive/2015.5.8 trusty main\n' | sudo tee -a /etc/apt/sources.list >/dev/null
         sudo apt-get -y update

top.sls

@@ -5,6 +5,10 @@ base:
     - common
     - servo-dependencies
 
+  'os:Ubuntu':
+    - match: grain
+    - ubuntu
+
   'servo-head':
     - buildbot.slave
     - android-dependencies

ubuntu/files/policy-rc.d

@@ -0,0 +1,2 @@
+#!/bin/sh
+exit 101

ubuntu/init.sls

@@ -0,0 +1,8 @@
+# Disable service autostart on package install
+# Use Salt to manage service [re-]start on package change
+/usr/sbin/policy-rc.d:
+  file.managed:
+    - user: root
+    - group: root
+    - mode: 755
+    - source: salt://{{ tpldir }}/files/policy-rc.d