Wait for job.id in Travis.Artifact

assets/scripts/app/models/artifact.coffee

@@ -8,6 +8,7 @@ require 'travis/model'
   init: ->
     @_super.apply this, arguments
 
+    @addObserver 'job.id', @fetchBody
     @fetchBody()
 
     @set 'queue', Ember.A([])
@@ -21,8 +22,11 @@ require 'travis/model'
     @incrementProperty('version')
 
   fetchBody: ->
+    if jobId = @get('job.id')
+      @removeObserver 'job.id', @fetchBody
+
       self = this
-    Travis.ajax.ajax "/jobs/#{@get('job.id')}/log.txt?cors_hax=true", 'GET',
+      Travis.ajax.ajax "/jobs/#{jobId}/log.txt?cors_hax=true", 'GET',
         dataType: 'text'
         contentType: 'text/plain'
         success: (data, textStatus, xhr) ->
@@ -31,7 +35,7 @@ require 'travis/model'
 
             # For some reason not all browsers can fetch this header
             unless logUrl
-            logUrl = self.s3Url("/jobs/#{self.get('job.id')}/log.txt")
+              logUrl = self.s3Url("/jobs/#{jobId}/log.txt")
 
             $.ajax
               url: logUrl