attempt-backport: simplify git steps

- Resetting *before* checkout is probably actually faulty logic as
described in
nodejs#100 (comment)

- Resetting after checkout is unnecessary because we check out the
origin/ branch so the HEAD becomes detached.

PR-URL: nodejs#107

scripts/attempt-backport.js

@@ -156,15 +156,10 @@ function attemptBackport (options, version, isLTS, cb) {
         debug(`error before exit, code: ${code}, on '${argsString}'`)
         return
       }
-      gitResetBefore()
+      gitRemoteUpdate()
     })
   }
 
-  function gitResetBefore () {
-    options.logger.debug(`resetting origin/v${version}.x-staging...`)
-    wrapCP('git', ['reset', `origin/v${version}.x-staging`, '--hard'], gitRemoteUpdate)
-  }
-
   function gitRemoteUpdate () {
     options.logger.debug('updating git remotes...')
     wrapCP('git', ['remote', 'update', '-p'], gitCheckout)
@@ -176,12 +171,7 @@ function attemptBackport (options, version, isLTS, cb) {
   }
 
   function gitClean_fd () {
-    wrapCP('git', ['clean', '-fd'], gitReset)
-  }
-
-  function gitReset () {
-    options.logger.debug(`resetting origin/v${version}.x-staging...`)
-    wrapCP('git', ['reset', `origin/v${version}.x-staging`, '--hard'], fetchDiff)
+    wrapCP('git', ['clean', '-fd'], fetchDiff)
   }
 
   function fetchDiff () {