[files_sharing] dont automatically update file_target if it starts wi…

…th a / (nextcloud#12548)

needed by craig/autoshare#15 when we explicitely set file_target
to present file in a subdir.

apps/files_sharing/lib/SharedMount.php

@@ -108,7 +108,11 @@ private function verifyMountPoint(\OCP\Share\IShare $share, array $mountpoints,
 		);
 
 		if ($newMountPoint !== $share->getTarget()) {
-			$this->updateFileTarget($newMountPoint, $share);
+			if (strpos($share->getTarget(),'/',1)) {
+				return $share->getTarget();
+			} else {
+				$this->updateFileTarget($newMountPoint, $share);
+			}
 		}
 
 		return $newMountPoint;