gclient: fix patch_project handling for the recipe engine

This is needed after https://github.com/luci/recipes-py/commit/d88f0c8311fdf2fe2d258d1032f84a251ceba83f

BUG=none

Review-Url: https://codereview.chromium.org/2091313003

recipe_modules/gclient/config.py

@@ -564,7 +564,9 @@ def infra(c):
 
   p = c.patch_projects
   p['luci-py'] = ('infra/luci', 'HEAD')
+  # TODO(phajdan.jr): remove recipes-py when it's not used for project name.
   p['recipes-py'] = ('infra/recipes-py', 'HEAD')
+  p['recipe_engine'] = ('infra/recipes-py', 'HEAD')
 
 @config_ctx(config_vars={'GIT_MODE': True})
 def infra_internal(c):  # pragma: no cover