Retrieve the backupPath from the storage provider itself

src/backups.js

@@ -215,16 +215,19 @@ function get(backupId, callback) {
     });
 }
 
+// This is not part of the storage api, since we don't want to pull the "format" logistics into that
 function getBackupFilePath(backupConfig, backupId, format) {
     assert.strictEqual(typeof backupConfig, 'object');
     assert.strictEqual(typeof backupId, 'string');
     assert.strictEqual(typeof format, 'string');
 
+    const backupPath = api(backupConfig.provider).getBackupPath(backupConfig);
+
     if (format === 'tgz') {
         const fileType = backupConfig.encryption ? '.tar.gz.enc' : '.tar.gz';
-        return path.join(backupConfig.prefix || backupConfig.backupFolder || '', backupId+fileType);
+        return path.join(backupPath, backupId+fileType);
     } else {
-        return path.join(backupConfig.prefix || backupConfig.backupFolder || '', backupId);
+        return path.join(backupPath, backupId);
     }
 }