get rid of .sage-backup files — useless.
get rid of .sage-backup files — useless.

DrXyzzy/smc,DrXyzzy/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc,tscholl2/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc