Roll recipe dependencies (trivial).

This is an automated CL created by the recipe roller. This CL rolls
recipe changes from upstream projects (fuchsia, recipe_engine) into this repository.

The build that created this CL was
https://ci.chromium.org/b/8780140585744985025

fuchsia:
https://fuchsia.googlesource.com/infra/recipes/+log/4eb5c4defd6f9029624c8229489d2937f5fd9f75~..f06eddc3263a28f6ad9f4080ec8febfb08e65358
  4eb5c4d (olivernewman@google.com)
      [shac] Improve function naming check highlighting
  e1cce59 (atyfto@google.com)
      [btu] Only attempt to run tests when testing pool is set
  febd601 (olivernewman@google.com)
      [shac] Add check for recipe function ordering
  a2fc1be (olivernewman@google.com)
      [cmake] Run black
  9393cc0 (olivernewman@google.com)
      [checkout] Increase Gerrit replication lag tolerance
  efa8071 (catduncan@google.com)
      [android_artifact_downloader] Fix artifact transformation logic
  d078a56 (josephry@google.com)
      [firebase_docs] Use correct python binary
  95971fe (nmulcahey@google.com)
      [macos_sdk] Use min version logic to select xcode
  ac9841b (atyfto@google.com)
      [artifacts] Roll blobfs-compression tool to latest
  2cba87a (atyfto@google.com)
      [build] Make "upload artifacts" step nesting neater
  f06eddc (global-integration-roller@fuchsia-infra.iam.gserviceaccount.com)
      [roll] Update pinned tools

recipe_engine:
https://chromium.googlesource.com/infra/luci/recipes-py/+log/ca8108133477b427170bee7494866a934a0a0fe8~..7f9b133838f1240a537916677161afd8129b234f
  ca81081 (vadimsh@chromium.org)
      [swarming] Update `swarming` CLI tool.
  a5c25e8 (iannucci@chromium.org)
      [recipes.py] Unset PYTHONPATH in case users have conflicting va...
  7f9b133 (chromium-autoroll@skia-public.iam.gserviceaccount.com)
      Roll CAS Client from edf7c1502de4 to 406fda74bafb

Please check the following references for more information:
- autoroller, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/workflow.md#autoroller
- rollback, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/workflow.md#rollback
- cross-repo dependencies, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/cross_repo.md

Use https://goo.gl/noib3a to file a bug.

Recipe-Tryjob-Bypass-Reason: Autoroller
Ignore-Freeze: Autoroller
Bugdroid-Send-Email: False
Change-Id: I89e60c5cf61a153298a444b5879347c079747bc6
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/148871
Bot-Commit: Recipe Deps Roller <recipe-deps-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Recipe Deps Roller <recipe-deps-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/infra/config/recipes.cfg b/infra/config/recipes.cfg
index bc85999..c7e5fb9 100644
--- a/infra/config/recipes.cfg
+++ b/infra/config/recipes.cfg
@@ -17,12 +17,12 @@
   "deps": {
     "fuchsia": {
       "branch": "refs/heads/main",
-      "revision": "4882e602fc90af0e96592905c9859d598e0d48cb",
+      "revision": "f06eddc3263a28f6ad9f4080ec8febfb08e65358",
       "url": "https://fuchsia.googlesource.com/infra/recipes"
     },
     "recipe_engine": {
       "branch": "refs/heads/main",
-      "revision": "d0c2ca6a542b48bea6371dfb3f443cd7ba3cbd7e",
+      "revision": "7f9b133838f1240a537916677161afd8129b234f",
       "url": "https://chromium.googlesource.com/infra/luci/recipes-py"
     }
   },
diff --git a/recipes.py b/recipes.py
index cccaaf3..24e4a66 100755
--- a/recipes.py
+++ b/recipes.py
@@ -235,6 +235,11 @@
   if not shutil.which(vpython):
     return f'Required binary is not found on PATH: {vpython}'
 
+  # We unset PYTHONPATH here in case the user has conflicting environmental
+  # things we don't want them to leak through into the recipe_engine which
+  # manages its environment entirely via vpython.
+  os.unsetenv("PYTHONPATH")
+
   argv = ([
     vpython, '-u', os.path.join(engine_path, 'recipe_engine', 'main.py'),
   ] + args)