> clearly Jeffrey's PR fixes a real and now reproducible problem so I'm declaring victory and have closed this issue now.  Thanks everyone!

Well done Jeffrey Kintscher! The test was failing randomly for years, I recall many bugs and many people complaining, but nobody succeeded to come up with a fix.

Note: this off-by-one looks magic to me, but I'm happy that it works :-)

    /*
     * NGROUPS_MAX is defined by POSIX.1 as the maximum
     * number of supplimental groups a users can belong to.
     * We have to increment it by one because
     * getgrouplist() returns both the supplemental groups
     * and the primary group, i.e. all of the groups the
     * user belongs to.
     */
    ngroups = 1 + MAX_GROUPS;