PRESUBMIT.py scripts might execute commands directly instead of using
CallCommand, so that the conversion to vpython is bypassed, resulting in
errors.

See e.g.
https://cs.chromium.org/chromium/src/third_party/blink/web_tests/PRESUBMIT.py?l=79

Bug: 1017410
Change-Id: If1943fe46cd2fc1e37b89aee14865429f884332b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1879493Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>