fix getting root entry when not provided by the share provider
fix getting root entry when not provided by the share provider

Signed-off-by: Robin Appelman <474ee9ee179b0ecf0bc27408079a0b15eda4c99d@icewind.nl>

andreas-p/nextcloud-server,nextcloud/server,jbicha/server,andreas-p/nextcloud-server,pmattern/server,endsguy/server,whitekiba/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,jbicha/server,pixelipo/server,nextcloud/server,whitekiba/server,Ardinis/server,andreas-p/nextcloud-server,whitekiba/server,jbicha/server,xx621998xx/server,pmattern/server,pixelipo/server,xx621998xx/server,nextcloud/server,endsguy/server,whitekiba/server,pmattern/server,pmattern/server,Ardinis/server,pixelipo/server,pmattern/server,xx621998xx/server,jbicha/server,pixelipo/server,endsguy/server,Ardinis/server,endsguy/server,Ardinis/server,pixelipo/server,whitekiba/server,michaelletzgus/nextcloud-server,jbicha/server,andreas-p/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,xx621998xx/server,endsguy/server,michaelletzgus/nextcloud-server,xx621998xx/server,Ardinis/server