The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/eclass-overlay/+/03e44fde2b50b9be9cd7c0b7c39ea7abf5543f88

commit 03e44fde2b50b9be9cd7c0b7c39ea7abf5543f88
Author: Manoj Gupta <manojgupta@chromium.org>
Date: Sun Apr 22 10:54:35 2018

Revert "Skip checks for user/group existence in user.eclass"

This reverts commit e53449ac8dd22ac152661751546834fa146298e2.

Reason for revert: Breaking chromiumos-sdk builder.
https://uberchromegw.corp.google.com/i/chromiumos/builders/chromiumos-sdk/builds/8715

BUG= chromium:835616 

Original change's description:
> Skip checks for user/group existence in user.eclass
>
> These checks cause enewuser/enewgroup calls to fail if the user/group
> already exists in the board sysroot but not in the sdk root. Sometimes
> users/groups need to be created in the sdk root when they already exist
> in the board sysroot. For example, in order to chown a file to user
> 'shill' in the ebuild for strongswan, 'shill' group needs to be created
> in the sdk root at the same time that it already exists in the board
> sysroot. This situation arises because the shill ebuild creates the
> shill user/group during pkg_preinst() (so they are created in the board
> sysroot only) but the strongswan ebuild needs to create the shill
> group during pkg_setup() (which creates the group in the sdk root as
> well).
>
> _write_entry_to_db() checks whether entries in the group or passwd file
> exists before adding the entries, so these checks are not necessary in
> the first place.
>
> BUG= chromium:834445 
> TEST=before: cannot reference shill group in ebuild for strongswan, even
> after calling enewgroup, after: can reference shill group
>
> Change-Id: I2f1f9400ab8d9be615bdb56279ebddf4926b2557
> Reviewed-on: https://chromium-review.googlesource.com/1017860
> Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
> Tested-by: Micah Morton <mortonm@chromium.org>
> Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
> Reviewed-by: Mike Frysinger <vapier@chromium.org>

Bug:  chromium:834445 
Change-Id: Id6e5ba1da72b16f7258ad486c335b7fed4c00327
Reviewed-on: https://chromium-review.googlesource.com/1023163
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/03e44fde2b50b9be9cd7c0b7c39ea7abf5543f88/eclass/user.eclass

Fixed https://uberchromegw.corp.google.com/i/chromiumos/builders/chromiumos-sdk/builds/8729