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/78f105cbebb6e8dc99d64638d400868851cb0c40 Add --train support to the new 'test' command (phajdan.jr@chromium.org)

TBR=iannucci@chromium.org

Change-Id: Iea696baa5091710c314309e063d7bd008953dcca
Recipe-Tryjob-Bypass-Reason: Autoroller
Bugdroid-Send-Email: False
Reviewed-on: https://chromium-review.googlesource.com/457078
Reviewed-by: <recipe-roller@chromium.org>
Commit-Queue: <recipe-roller@chromium.org>

infra/config/recipes.cfg

@@ -4,5 +4,5 @@ deps {
   project_id: "recipe_engine"
   url: "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git"
   branch: "master"
-  revision: "57a75df505dfe20cb1aa6b7536231e56267fa2b8"
+  revision: "78f105cbebb6e8dc99d64638d400868851cb0c40"
 }