Ensure an item is passed to pkg_job_add_req()
pkg_jobs_universe_get_local() can return NULL, not sure how to handle it here.

This would eventually crash in pkg_get() later anyhow due to NULL
pkg
Fix pkg-fetch -d. unit can be NULL here.

Issue:	#955
pkg-fetch.8: Remove reference to removed mirror mode
Update comment for what is in digest
Update to pre-alpha11