Error obtaining access token while configuring Github integration

The problem:

While configuring Github integration, the setup screen returns "error obtain access token" as in the following screenshots:

The following appears on atlassian-jira.log:

2014-04-08 10:32:45,944 http-bio-8622-exec-15 WARN admin 632x331x1 1ycok0n 192.168.10.136 /secure/admin/AddGithubOrganization!finish.jspa [spi.github.webwork.AddGithubOrganization] Error obtaining access token. Cannot access https://github.com from Jira.
2014-04-08 10:32:45,944 http-bio-8622-exec-15 WARN admin 632x331x1 1ycok0n 192.168.10.136 /secure/admin/AddGithubOrganization!finish.jspa [spi.github.webwork.AddGithubOrganization] Caused by: https://github.com/login/oauth/access_token

Current behavior:

If you click "Try Again" it redirects you to Github 404 page. If you click "Cancel" you see that the integration is set, but not all repositories appear on the list.

The only way to get the full repositories list is by selecting "Refresh list" as in the screenshot bellow:

Expected behavior:

The setup screen should complete the operation without any error and the list of repositories should be display without the need to select "Refresh list".