Roll recipe dependencies (trivial).

This is an automated CL created by the recipe roller. This CL rolls recipe
changes from upstream projects (e.g. depot_tools) into downstream projects
(e.g. tools/build).

More info is at https://goo.gl/zkKdpD. Use https://goo.gl/noib3a to file a bug
(or complain)

recipe_engine:
  https://crrev.com/be22c9a16dd89f9780e193a24edd98346870271d Formally define step config, pass to stream. (dnj@chromium.org)
  https://crrev.com/8ad49e0698f1e74e3f500fda6ca5b65a2af29fd0 Add better documentation, trigger namedtuple. (dnj@chromium.org)

TBR=martiniss@chromium.org,phajdan.jr@chromium.org
BUG=None,chromium:628770

Recipe-Tryjob-Bypass-Reason: Autoroller
Bugdroid-Send-Email: False
Review-Url: https://codereview.chromium.org/2338573002

infra/config/recipes.cfg

@@ -5,5 +5,5 @@ deps {
   project_id: "recipe_engine"
   url: "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git"
   branch: "master"
-  revision: "227f56ba6353986a7fe6d56fb283ad73c84e94d9"
+  revision: "8ad49e0698f1e74e3f500fda6ca5b65a2af29fd0"
 }