title: Checksum mismatch after code sign Electron Builder / Updater
body: <p>After running electron-builder for Windows / NSIS during a build process, our dev-ops team set a build script that runs to code sign the exe before deployment. After it gets to the server, electron-updater fails with a sha512 checksum mismatch (which the error occurs during the install, after it has been fully downloaded). I have also tried pulling the exe file down from the server and running a codesign util from Visual Studio CMD, and then re-uploading. The auto updater also fails with the same error.</p>
  
  <p>Is it not possible to sign the exe <em>after it has been generated</em>, and to still allow for the auto updater to work?</p>
  
  <p><strong>Signing:</strong></p>
  
  <p><code>signtool.exe sign /tr http://timestamp.digicert.com /td sha256 /fd sha256 /sha1 value "path"</code></p>
  
  <p><strong>Log:</strong></p>
  
  <p><code>Error: sha512 checksum mismatch, expected [value], got [different value]</code></p>
  
  <p><strong>Configuration in package.json:</strong></p>
  
  <pre><code>"build": {
      "appId": "com.stripped.stripped.stripped",
      "directories": {
          "output": "dist-exe",
          "app": "dist"
      },
      "win": {
          "target": "nsis",
          "icon": "dist/assets/favicon/favicon-256x256.ico",
          "verifyUpdateCodeSignature": false,
          "publish": {
              "provider": "generic",
              "url": "##{ElecronAppUpdaterLocation}##"
          }
      },
      "nsis": {
          "artifactName": "Setup_${version}.${ext}",
          "installerIcon": "dist/assets/favicon/favicon-256x256.ico",
          "installerHeaderIcon": "dist/assets/favicon/favicon-256x256.ico"
      }
  }
  </code></pre>