GitLab

Builders don't (and shouldn't) have global git user name/email
configured, and the recipe only configures git user in the Chromium
checkout (the recipe doesn't know about the tmp WPT checkout). When git
user cannot be found (neither in the repo or globally), `git commit`
will fail. (Previously, we didn't notice the issue on BuildBot because
the bot had some leftover global configurations from an earlier version
of the recipe.)

To make sure we always have a git user configured, this change
explicitly sets git user name & email in the tmp WPT checkout to the bot
account. It is still safe to run the script manually because GitHub
allows committers to be different from the uploader.

Besides, remove an unnecessary pair of quotes in a format string for
`git show`; we don't use shell to start subprocesses so spaces don't
need to be quoted.

Bug: 803111
Change-Id: Ife020c8a18120ff607b8802c32cf9539bf6a36c9
Reviewed-on: https://chromium-review.googlesource.com/1258977
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596290}