Tweak alignment of only use of job_msg_debug

The job_msg_debug added a "debug: " prefix to every message, which shifted
the distfile message so nothing lines up.  The prefix "status" doesn't
even make much sense, so I just removed it so the debug log line looks
like "Debug:  <origin> ..." instead of "Debug: Status  <origin>".  The
log still makes sense to me.