Cosmetic: warning printed when pkg is upgraded and options were set with the -o option

[dsg22]

When passing config options to pkg with -o and a pkg upgrade is available, after upgrading itself and re-running, the second pkg instance will print warnings like: pkg: option EVENT_PIPE is defined in the environment to '/tmp/tmp9szcx6g9/pkg_fifo' but command line option redefines it

Perhaps the -o option should be skipped for the latter run if the options are already set in the environment? Or those options specified with -o could be filtered out from the environment?

This is obviously a minor cosmetic issue only.