Ruby

merge revision(s) 63698: [Backport #14856]

    lib/drb/extservm.rb (service): do not return `false'

    invoke_service_command may set entries in @servers to `false',
    making it incompatible with the intended use of the
    safe navigation operator.

    This caused occasional DRb test failures, but they were hidden
    with automatic retry.

    [ruby-core:87524] [Bug #14856]

    Fixes: r53111 ("use safe navigation operator")
            commit 059c9c1cf371e049c7481c78b76e9620da52757f [GH-1142]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@64128 b2dd03c8-39d4-4d8f-98ff-823fe69b080e