update_chroot: Don't reinstall binpkgs based on date

The combination of --update, --usepkgonly, and --deep causes emerge to
reinstall all binpkgs that have a newer BUILD_TIME.  Since we upload new
prebuilts when the SDK builder runs, this causes a large fraction of the
entire chroot to get reinstalled every couple of days.

What we really want is for changed/updated packages and their
dependencies to be reinstalled, so --deep is still needed.  Pass
--rebuilt-binaries=n to avoid reinstalling packages where the only
change is the build timestamp.

TEST=./update_chroot installs 8 packages instead of 485

Change-Id: Ia3f8f5a9251cdcbe463dd03bda5ed7e54633f3d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3456584
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Tested-by: Benjamin Gordon <bmgordon@chromium.org>
Commit-Queue: Benjamin Gordon <bmgordon@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed