useradd_base.bbclass: prevent variable expansion in $opts
Many user/group operations will involve hashes which will include '$'
followed by a number or even possibly an env. variable name. Passing
$opts to flock requires that we take additional precautions to prevent
the unexpected expansion of these instances.
This was found by an image which used usermod operations to set the
password hash for root. The image could not be logged-in to and
examining /etc/shadow clearly showed that $0 and other $* variables
had been expanded unexpectedly. This change returnes the behavior to
what existed prior to commit
2ebf697b46c42cee8bfa6d2e6087397f8cce385c
[useradd_base.bbclass: replace retry logic with flock].
Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
