for {
		// Step 1 create slice with all top versions.
		tops = tops[:0]
		var topSig xlMetaV2VersionHeader
		consistent := true // Are all signatures consistent (shortcut)
		for _, vers := range versions {
			if len(vers) == 0 {
				consistent = false
				continue
			}
			ver := vers[0]
			if len(tops) == 0 {
				consistent = true
				topSig = ver.header