Comment # 2 on bug 1020870 from Dr. Werner Fink

Indeed the old screen shows in manual page

       -L   tells screen to turn on automatic output logging for the windows.

and screen 4.5.0 does it now combine with an other feature

       -L   tells screen to turn on automatic output logging for the windows.
            By  default,  logfile's  name  is screenlog.1. You can sets new
            name: add it right after -L option e.g. "screen -L my_logfile".

IMHO the new behaviour option -L should ignore not only an empty line but also
all behind a leading - including the `-' its self.