Follow up to crrev.com/c/2125626.

This allows depot_tools commands to run successfully when depot_tools is
installed in a path containing spaces.

Change-Id: I8f99dbdcb3b1acf27d51ce26b6153f643b8d4dcd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2127675
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>