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/ab4c628b8432cb3d3dbcee32a539f486115a329b Retry errors during fetch (phajdan.jr@chromium.org)

R=phajdan.jr@chromium.org
BUG=chromium:618127

TBR=martiniss@chromium.org,phajdan.jr@chromium.org

Review-Url: https://codereview.chromium.org/2135563002

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: "5f18b96cc381e6c9df75bab13cdb99004e8b6779"
+  revision: "ab4c628b8432cb3d3dbcee32a539f486115a329b"
 }