Fix format migration regression (#5668)

Migration regression got introduced in 9083bc152e
adding more unit tests to catch this scenario, we need to fix this by
re-writing the formats after the migration to 'V3'.

This bug only happens when a user is migrating directly from V1 to V3,
not from V1 to V2 and V2 to V3.

Added additional unit tests to cover these situations as well.

Fixes #5667

cmd/prepare-storage.go

@@ -147,6 +147,20 @@ func waitForFormatXL(firstDisk bool, endpoints EndpointList, setCount, disksPerS
 				return initFormatXL(endpoints, setCount, disksPerSet)
 			}
 
+			// Following function is added to fix a regressions which was introduced
+			// in release RELEASE.2018-03-16T22-52-12Z after migrating v1 to v2 to v3.
+			// This migration failed to capture '.This' field properly which indicates
+			// the disk UUID association. Below function is called to handle and fix
+			// this regression, for more info refer https://github.com/minio/minio/issues/5667
+			if err = fixFormatXLV3(endpoints, formatConfigs); err != nil {
+				return nil, err
+			}
+
+			// If any of the .This field is still empty we wait them to be fixed.
+			if formatXLV3ThisEmpty(formatConfigs) {
+				continue
+			}
+
 			format, err = getFormatXLInQuorum(formatConfigs)
 			if err == nil {
 				for i := range formatConfigs {