Use always_run v can_fail_build

scripts/slave/recipes/chromium.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 DEPS = [
   'chromium',
   'gclient',
   'properties',
+  'python',
 ]
 
 def GenSteps(api):
   # TODO(iannucci): Make a standard way to specify configuration in the recipe
   #                 inputs. Such a design should be able to accept modified
   #                 config blobs as well (hopefully readably delta-encoded).
   config_vals = {'GIT_MODE': True}
   config_vals.update(
     dict((str(k),v) for k,v in api.properties.iteritems() if k.isupper())
   )
   api.chromium.set_config('chromium', **config_vals)
 
   yield (
     api.gclient.checkout(),
     api.chromium.runhooks(),
     api.chromium.compile(),
   )
 
+  yield api.python.inline('last step', 'print "last step"')
+
 
 def GenTests(api):
   for plat in ('win', 'mac', 'linux'):
     for bits in (32, 64):
       yield 'basic_%s_%s' % (plat, bits), {
         'mock': {'platform': {'name': plat}},
         'properties': {'TARGET_BITS': bits},
       }
+  yield 'fail', {
+    'step_mocks': {
+      'compile': {
+        '$R': 1
+      }
+    }
+  }