Regarding the from upstream, are you providing that just as an FYI, or are you looking for automatic mirroring from upstream? Setting up mirroring is a more significant undertaking.

I'd just like to create a new branch in our tree with the source from that commit tag. I don't need it to mirror.

Done. https://chromium-review.googlesource.com/#/admin/projects/chromiumos/third_party/u-boot,branches

Looks good, thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/b09c9caf27ab0a9b3f656af58f00eee539a38bab

commit b09c9caf27ab0a9b3f656af58f00eee539a38bab
Author: chrome-bot <chrome-bot@chromium.org>
Date: Thu Aug 03 02:23:17 2017

u-boot: Update chromeos-version.sh for recent versions

The current method of obtaining the version number relies on running the
Makefile with a special target. This does not work with recent U-Boot
versions which require the source to be configured before it is built.

In any case the version information is in a well known format and can be
read easily without running the Makefile. Update the code to handle this.

BUG= chromium:735987 
TEST=Run script with both 2017.05 and 2013.06:
~/cosarm/src/third_party/chromiumos-overlay/sys-boot/chromeos-u-boot/\
files/chromeos-version.sh ~/cosarm/src/third_party/u-boot/files

Change-Id: I73579f58d750d3ae130a9b195145ddac6110607b
Reviewed-on: https://chromium-review.googlesource.com/594930
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/b09c9caf27ab0a9b3f656af58f00eee539a38bab/sys-boot/chromeos-u-boot/files/chromeos-version.sh

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/manifest/+/519411416915602298562accbafeee86d9e3a59d

commit 519411416915602298562accbafeee86d9e3a59d
Author: Simon Glass <sjg@chromium.org>
Date: Fri Aug 04 00:11:02 2017

Switch over to newer U-Boot

The current U-Boot is very old and (for example) patman lacks some
features. Update it to a newer branch.

BUG= chromium:735987 
TEST=copy changes to .repo/manifest; repo sync
See that the new version is synced
Signed-off-by: Simon Glass <sjg@chromium.org>

Change-Id: Id58b7d82fd452ba648c99fc0c3b9bed6bbe66a6b
Reviewed-on: https://chromium-review.googlesource.com/594210
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/519411416915602298562accbafeee86d9e3a59d/full.xml

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/chromeos/manifest-internal/+/41d3e54f454cb107e9d6a2b96feaaf70ce0f5cfe

commit 41d3e54f454cb107e9d6a2b96feaaf70ce0f5cfe
Author: Simon Glass <sjg@chromium.org>
Date: Fri Aug 04 22:39:11 2017