title: When " flutter upgrade", I get "Permission denied" error
body: <p>I would like to build a web application with Flutter. I followed this instruction. <a href="https://flutter.dev/docs/get-started/web" rel="nofollow noreferrer">https://flutter.dev/docs/get-started/web</a>
  I use Windows 10, Windows Subsystems for Linux, Debian 10.</p>
  
  <p>I installed Flutter SDK in <code>~/development/</code> directory and have already set the path.</p>
  
  <p>I input this.</p>
  
  <pre><code>flutter channel beta
  </code></pre>
  
  <p>And get this result.</p>
  
  <pre><code>Switching to flutter channel 'beta'...
  git: From https://github.com/flutter/flutter
  git:    5f21edf8b..b041144f8  stable         -&gt; origin/stable
  git:  * [new branch]          CareF-macrobenchmark-typo-fix -&gt; origin/CareF-macrobenchmark-typo-fix
  git:    c0d537ad3..311ad4bde  dart_development_service -&gt; origin/dart_development_service
  git:    456d80b9d..2f7a59a8d  dev            -&gt; origin/dev
  git:    5f21edf8b..b041144f8  flutter-1.17-candidate.3 -&gt; origin/flutter-1.17-candidate.3
  git:  * [new branch]          flutter-1.19-candidate.2 -&gt; origin/flutter-1.19-candidate.2
  git:  * [new branch]          flutter-1.19-candidate.3 -&gt; origin/flutter-1.19-candidate.3
  git:  * [new branch]          flutter-1.19-candidate.4 -&gt; origin/flutter-1.19-candidate.4
  git:    eacd1c8de..746749244  master         -&gt; origin/master
  git:  * [new tag]             1.17.3         -&gt; 1.17.3
  git:  * [new tag]             1.19.0-2.0.pre -&gt; 1.19.0-2.0.pre
  git:  * [new tag]             1.19.0-3.0.pre -&gt; 1.19.0-3.0.pre
  git:  * [new tag]             1.19.0-4.0.pre -&gt; 1.19.0-4.0.pre
  git: Switched to a new branch 'beta'
  git: Branch 'beta' set up to track remote branch 'beta' from 'origin'.
  Successfully switched to flutter channel 'beta'.
  To ensure that you're on the latest build from this channel, run 'flutter
  upgrade'
  </code></pre>
  
  <p>Next, I input this.</p>
  
  <pre><code>flutter upgrade
  </code></pre>
  
  <p>Then, I get this.</p>
  
  <pre><code>Downloading Dart SDK from Flutter engine ef9215ceb2884ddf520d321bcd822d1461330876...
  mv: cannot move '/home/kazu/development/flutter/bin/cache/dart-sdk' to
  '/home/kazu/development/flutter/bin/cache/dart-sdk.old': Permission denied
  </code></pre>
  
  <p>So, I read this NOTE. <a href="https://flutter.dev/docs/get-started/web#set-up" rel="nofollow noreferrer">https://flutter.dev/docs/get-started/web#set-up</a></p>
  
  <pre><code>The flutter upgrade command silently fails when origin points to a personal fork. 
  To validate that origin points to https://github.com/flutter/flutter.git, 
  run the following commands in the root directory of your local copy of the 
  https://github.com/flutter/flutter repository:
  </code></pre>
  
  <p>Then, I input this.</p>
  
  <pre><code>cd ~/development/flutter/
  git remote get-url origin
  </code></pre>
  
  <p>Then my terminal returned this.</p>
  
  <pre><code>https://github.com/flutter/flutter.git
  </code></pre>
  
  <p>So, I tried again.</p>
  
  <pre><code>flutter upgrade
  </code></pre>
  
  <p>I got the same result.</p>
  
  <pre><code>Downloading Dart SDK from Flutter engine ef9215ceb2884ddf520d321bcd822d1461330876...
  mv: cannot move '/home/kazu/development/flutter/bin/cache/dart-sdk' to
  '/home/kazu/development/flutter/bin/cache/dart-sdk.old': Permission denied
  </code></pre>
  
  <p>Next, I tried <code>sudo</code></p>
  
  <pre><code>sudo flutter upgrade
  </code></pre>
  
  <p>Then I got this.</p>
  
  <pre><code>sudo: flutter: command not found
  </code></pre>
  
  <p>Could you give me any advice please?</p>