When a group name is duplicated between USERADD_PARAM and
GROUPADD_PARAM, this class tries to add it twice which results in
failure of the groupadd command.
(From OE-Core rev: 5b84cc895500c28674d2a7b7c2dd618cf8fb30e9)
Signed-off-by: David Vincent <freesilicon@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>