EPELリポジトリメタデータを抽出できません。

Scientific LinuxによるNginxのインストールこの文書失敗する：

[vagrant@localhost ~]$ sudo su -c 'rpm -Uvh http://dl.fedoraproject.org/pub/epe
l/6/x86_64/epel-release-6-8.noarch.rpm'
Retrieving http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch
.rpm
warning: /var/tmp/rpm-tmp.gdSOR9: Header V3 RSA/SHA256 Signature, key ID 0608b89
5: NOKEY
Preparing...                ########################################### [100%]
   1:epel-release           ########################################### [100%]
[vagrant@localhost ~]$ sudo yum install nginx
Loaded plugins: security
Error: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Pl
ease verify its path and try again
[vagrant@localhost ~]$

バージョン情報

[vagrant@localhost ~]$ uname -a
Linux localhost.localdomain 2.6.32-431.el6.x86_64 #1 SMP Thu Nov 21 13:35:52 CST
 2013 x86_64 x86_64 x86_64 GNU/Linux
[vagrant@localhost ~]$ cat /etc/*{release,version}
Scientific Linux release 6.5 (Carbon)
Scientific Linux release 6.5 (Carbon)
cat: /etc/*version: No such file or directory
[vagrant@localhost ~]$

メモ: sudo yum update -ynginxのインストールを開始する前の問題

他のパッケージのインストールを無効にする

[vagrant@localhost ~]$ sudo yum install vim -y
Loaded plugins: security
Error: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Pl
ease verify its path and try again
[vagrant@localhost ~]$

URLGRABBERデバッガログ

2014-08-03 14:22:44,437 attempt 1/10: https://mirrors.fedoraproject.org/metalink
?repo=epel-6&arch=x86_64
INFO:urlgrabber:attempt 1/10: https://mirrors.fedoraproject.org/metalink?repo=ep
el-6&arch=x86_64
2014-08-03 14:22:44,438 opening local file "/var/cache/yum/x86_64/6.5/epel/metal
ink.xml.tmp" with mode wb
INFO:urlgrabber:opening local file "/var/cache/yum/x86_64/6.5/epel/metalink.xml.
tmp" with mode wb
* About to connect() to mirrors.fedoraproject.org port 443 (#0)
*   Trying IP... * connected
* Connected to mirrors.fedoraproject.org (IP) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
* NSS error -8018
* Closing connection #0
* Problem with the SSL CA cert (path? access rights?)
2014-08-03 14:22:50,071 exception: [Errno 14] PYCURL ERROR 77 - "Problem with th
e SSL CA cert (path? access rights?)"
INFO:urlgrabber:exception: [Errno 14] PYCURL ERROR 77 - "Problem with the SSL CA
 cert (path? access rights?)"
2014-08-03 14:22:50,072 retrycode (14) not in list [-1, 2, 4, 5, 6, 7], re-raisi
ng
INFO:urlgrabber:retrycode (14) not in list [-1, 2, 4, 5, 6, 7], re-raising
Error: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Pl
ease verify its path and try again

nginx インストールの前後に yum update 出力

[vagrant@localhost ~]$ sudo yum update -y
Loaded plugins: security
Error: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Pl
ease verify its path and try again
[vagrant@localhost ~]$

yum --disablerepo="epel" アップデート

[vagrant@localhost ~]$ sudo yum --disablerepo="epel" update
Loaded plugins: security
Setting up Update Process
No Packages marked for Update