allow ".." in folder names
allow ".." in folder names

".." are valid in folder names, only ".." by itself is invalid
fix for #18987
whitekiba/server,owncloud/core,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,whitekiba/server,lrytz/core,xx621998xx/server,endsguy/server,michaelletzgus/nextcloud-server,IljaN/core,jbicha/server,owncloud/core,owncloud/core,whitekiba/server,pmattern/server,lrytz/core,bluelml/core,michaelletzgus/nextcloud-server,xx621998xx/server,endsguy/server,cernbox/core,lrytz/core,whitekiba/server,cernbox/core,sharidas/core,pixelipo/server,pmattern/server,pollopolea/core,jbicha/server,pixelipo/server,pixelipo/server,Ardinis/server,sharidas/core,endsguy/server,pollopolea/core,sharidas/core,xx621998xx/server,pmattern/server,jbicha/server,endsguy/server,andreas-p/nextcloud-server,sharidas/core,owncloud/core,lrytz/core,lrytz/core,cernbox/core,pollopolea/core,IljaN/core,nextcloud/server,whitekiba/server,xx621998xx/server,Ardinis/server,nextcloud/server,pixelipo/server,Ardinis/server,pollopolea/core,pmattern/server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server,phil-davis/core,nextcloud/server,jbicha/server,andreas-p/nextcloud-server,bluelml/core,IljaN/core,cernbox/core,pmattern/server,bluelml/core,xx621998xx/server,IljaN/core,andreas-p/nextcloud-server,bluelml/core,cernbox/core,IljaN/core,pixelipo/server,sharidas/core,bluelml/core,Ardinis/server,Ardinis/server,endsguy/server,jbicha/server,pollopolea/core,owncloud/core