fix https://github.com/sagemathinc/smc/issues/824 -- "jupyter server broken for directory name with backslashes"
fix https://github.com/sagemathinc/smc/issues/824 -- "jupyter server broken for directory name with backslashes"

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