Merge branch 'test/additional-software-with-locked-persistence-robustness' into 'stable'

Test suite: make "Scenario: The Additional Software dpkg hook…" scenario more robust

See merge request tails/tails!93

features/step_definitions/additional_software_packages.rb

@@ -148,7 +148,7 @@ end
 Then /^the Additional Software dpkg hook has been run for package "([^"]*)" and notices the persistence is locked$/ do |package|
   asp_logs = "#{ASP_STATE_DIR}/log"
   assert(!$vm.file_empty?(asp_logs))
-  try_for(120) do
+  try_for(180, delay: 2) do
     $vm.execute(
       "grep -E '^.*New\spackages\smanually\sinstalled:\s.*#{package}.*$' " \
       "#{asp_logs}"

features/step_definitions/apt.rb

@@ -56,7 +56,7 @@ When /^I update APT using apt$/ do
 end
 
 def wait_for_package_installation(package)
-  try_for(2 * 60) do
+  try_for(2 * 60, delay: 3) do
     $vm.execute_successfully("dpkg -s '#{package}' 2>/dev/null " \
                              "| grep -qs '^Status:.*installed$'")
   end
@@ -81,7 +81,7 @@ Then /^I install "(.+)" using apt$/ do |package|
 end
 
 def wait_for_package_removal(package)
-  try_for(3 * 60) do
+  try_for(3 * 60, delay: 3) do
     # Once purged, a package is removed from the installed package status
     # database and "dpkg -s" returns a non-zero exit code
     !$vm.execute("dpkg -s #{package}").success?