Add errCorruptedFormat to list of ignored errors for metadata operations. (#4447)

Fixes listing of objects where xl.json is empty or corrupted to skip to the next disk/server (issue 4354).

cmd/xl-v1-metadata.go

@@ -293,7 +293,7 @@ func pickValidXLMeta(metaArr []xlMetaV1, modTime time.Time) (xlMetaV1, error) {
 }
 
 // list of all errors that can be ignored in a metadata operation.
-var objMetadataOpIgnoredErrs = append(baseIgnoredErrs, errDiskAccessDenied, errVolumeNotFound, errFileNotFound, errFileAccessDenied)
+var objMetadataOpIgnoredErrs = append(baseIgnoredErrs, errDiskAccessDenied, errVolumeNotFound, errFileNotFound, errFileAccessDenied, errCorruptedFormat)
 
 // readXLMetaParts - returns the XL Metadata Parts from xl.json of one of the disks picked at random.
 func (xl xlObjects) readXLMetaParts(bucket, object string) (xlMetaParts []objectPartInfo, err error) {