Some users call ninja/autoninja inside a depot_tools.on_path() context.
e.g. https://source.chromium.org/chromium/chromium/tools/build/+/main:recipes/recipes/chromium_upload_clang.py;l=92;drc=5bf3de010da6bd44d776f98c136e3b41f82cdfe8

Tested on a led build.
https://ci.chromium.org/swarming/task/5b802dcdfe0a2810

Bug: 931218
Recipe-Nontrivial-Roll: build
Recipe-Nontrivial-Roll: build_limited
Recipe-Nontrivial-Roll: chrome_release
Recipe-Nontrivial-Roll: chromiumos
Recipe-Nontrivial-Roll: infra
Change-Id: If3ece36c1d6590d30bc071deba6387d39b7c33a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3704921Reviewed-by: Alexander Thomas <athom@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Junji Watanabe <jwata@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>