add the canvas version to delayed_jobs_pool proc name

test plan: with a VERSION file in your rails root, run delayed jobs, the
process name will include the contents of the VERSION file. with no
VERSION file, it won't.

Change-Id: I773ff4ace5facdb48d415ad7528daaf761aeab1d
Reviewed-on: https://gerrit.instructure.com/40162
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>

app/views/plugins/index.html.erb

@@ -5,7 +5,7 @@
 %>
 
 <span class="small pull-right">
-  Revision: <%= Canvas.revision %>
+  Revision: <%= Canvas.revision || t('#canvas_revision_unknown', "Unknown") %>
 </span>
 
 <h2>

lib/canvas.rb

@@ -145,11 +145,12 @@ module Canvas
   end
 
   def self.revision
-    return @revision unless @revision.nil?
-    if File.file?(Rails.root+"VERSION")
-      @revision = File.readlines(Rails.root+"VERSION").first.try(:strip)
+    return @revision if defined?(@revision)
+    @revision = if File.file?(Rails.root+"VERSION")
+      File.readlines(Rails.root+"VERSION").first.try(:strip)
+    else
+      nil
     end
-    @revision ||= I18n.t(:canvas_revision_unknown, "Unknown")
   end
 
   # protection against calling external services that could timeout or misbehave.

vendor/plugins/delayed_job/lib/delayed/pool.rb

@@ -82,12 +82,20 @@ class Pool
 
   protected
 
+  def procname
+    name = "delayed_jobs_pool"
+    if Canvas.revision
+      name = "#{name} (#{Canvas.revision})"
+    end
+    name
+  end
+
   def start
     load_rails
     tail_rails_log unless @daemon
 
     say "Started job master", :info
-    $0 = "delayed_jobs_pool"
+    $0 = procname
     apply_config
 
     # fork to handle unlocking (to prevent polluting the parent with worker objects)