When a custom workdir is used for the checkout, it differs from the workdir
for temporary state files. In this case, code ensuring the existing of the
parent dir wasn't executed.

NOTRY=true

Bug: v8:7735
Change-Id: Idc81b50bb8f880dea45fde08ba4d437c91e96a37
Reviewed-on: https://chromium-review.googlesource.com/1049552Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53068}