rename to checkBackupPreconditions

since this is called only by the backup logic

src/storage/s3.js

@@ -2,7 +2,7 @@
 
 exports = module.exports = {
     getRootPath,
-    checkPreconditions,
+    checkBackupPreconditions,
 
     upload,
     exists,
@@ -98,7 +98,7 @@ function getRootPath(apiConfig) {
     return apiConfig.prefix;
 }
 
-async function checkPreconditions(apiConfig, dataLayout) {
+async function checkBackupPreconditions(apiConfig, dataLayout) {
     assert.strictEqual(typeof apiConfig, 'object');
     assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
 }