fix: Add support for preserving mtime for replication (#9995)

This PR is needed for bucket replication support

cmd/erasure-object.go

@@ -698,9 +698,6 @@ func (er erasureObjects) putObject(ctx context.Context, bucket string, object st
 		})
 	}
 
-	// Save additional erasureMetadata.
-	modTime := UTCNow()
-
 	opts.UserDefined["etag"] = r.MD5CurrentHexString()
 
 	// Guess content-type from the extension if possible.
@@ -708,6 +705,11 @@ func (er erasureObjects) putObject(ctx context.Context, bucket string, object st
 		opts.UserDefined["content-type"] = mimedb.TypeByExtension(path.Ext(object))
 	}
 
+	modTime := opts.MTime
+	if opts.MTime.IsZero() {
+		modTime = UTCNow()
+	}
+
 	// Fill all the necessary metadata.
 	// Update `xl.meta` content on each disks.
 	for index := range partsMetadata {