OK, all the phases should have messages.

rakefiles/prereqs.rake

@@ -12,21 +12,23 @@ task :install_prereqs => [:install_node_prereqs, :install_ruby_prereqs, :install
 
 desc "Install all node prerequisites for the lms and cms"
 task :install_node_prereqs => "ws:migrate" do
-    when_changed('', 'package.json') do
+    unchanged = 'Node requirements unchanged, nothing to install'
+    when_changed(unchanged, 'package.json') do
         sh('npm install')
     end unless ENV['NO_PREREQ_INSTALL']
 end
 
 desc "Install all ruby prerequisites for the lms and cms"
 task :install_ruby_prereqs => "ws:migrate" do
-    when_changed('', 'Gemfile') do
+    unchanged = 'Ruby requirements unchanged, nothing to install'
+    when_changed(unchanged, 'Gemfile') do
         sh('bundle install')
     end unless ENV['NO_PREREQ_INSTALL']
 end
 
 desc "Install all python prerequisites for the lms and cms"
 task :install_python_prereqs => "ws:migrate" do
-    unchanged = 'Requirements files unchanged, nothing to install'
+    unchanged = 'Python requirements unchanged, nothing to install'
     when_changed(unchanged, 'requirements/**/*') do
         ENV['PIP_DOWNLOAD_CACHE'] ||= '.pip_download_cache'
         sh('pip install --exists-action w -r requirements/edx/base.txt')