Skip update if the installer is not found on the server update

2018-10-24 14:39:27 1536 1312 DEBUG    nxdrive.updater.base Polling u'https://3c498de9.ngrok.io' for update, the current version is '3.1.2'
2018-10-24 14:39:27 1536 1312 DEBUG    urllib3.connectionpool Starting new HTTPS connection (1): 3c498de9.ngrok.io
2018-10-24 14:39:27 1536 1312 DEBUG    urllib3.connectionpool https://3c498de9.ngrok.io:443 "GET /versions.yml HTTP/1.1" 200 1027
2018-10-24 14:39:27 1536 1312 DEBUG    urllib3.connectionpool Starting new HTTP connection (1): 192.168.0.13
2018-10-24 14:39:27 1536 1312 DEBUG    urllib3.connectionpool http://192.168.0.13:8080 "GET /nuxeo/drive_browser_login.jsp HTTP/1.1" 401 262
2018-10-24 14:39:27 1536 1312 WARNING  nxdrive.wui.application A new version 4.0.0 is available.
2018-10-24 14:39:27 1536 1312 DEBUG    nxdrive.notification Sending Notification(level='info' title=u'Update available' uid='AutoUpdate' unique=2)
2018-10-24 14:39:27 1536 1312 INFO     nxdrive.updater.base Starting application update process to version 4.0.0
2018-10-24 14:39:27 1536 1312 INFO     nxdrive.updater.base Fetching version '4.0.0' from update site u'https://3c498de9.ngrok.io' into 'c:\\users\\windows7\\appdata\\local\\temp\\7fb3602709584bbe855e41487f31a852_nuxeo-drive-4.0.0.exe'
2018-10-24 14:39:27 1536 1312 DEBUG    urllib3.connectionpool Starting new HTTPS connection (1): 3c498de9.ngrok.io
2018-10-24 14:39:28 1536 1312 DEBUG    urllib3.connectionpool https://3c498de9.ngrok.io:443 "GET /beta/nuxeo-drive-4.0.0.exe HTTP/1.1" 404 469
2018-10-24 14:39:28 1536 1312 TRACE    nxdrive.updater.base Integrity check [SHA256] for 'c:\\users\\windows7\\appdata\\local\\temp\\7fb3602709584bbe855e41487f31a852_nuxeo-drive-4.0.0.exe': good='3d72f2bde31e2934cff33d10939e2f14dc232b2734478877c211d2d214086729', found='eef948e1d511bd86ff673f904bf0a97106d5395f0b7ed2cfb043da7ccc6ca6dd'
2018-10-24 14:39:28 1536 1312 ERROR    nxdrive.updater.base Auto-update error
Traceback (most recent call last):
  File "nxdrive\updater\base.py", line 275, in _handle_status
  File "nxdrive\updater\base.py", line 134, in update
  File "nxdrive\updater\base.py", line 158, in _download
UpdateError: Installer integrity check failed for 'nuxeo-drive-4.0.0.exe'