我用的是CentOS6.5系统，在yum update时报如下错误：
Running rpm_check_debug
ERROR with rpm_check_debug vs depsolve:
httpd >= 2.2.15-24 is needed by mod_nss-1.0.8-19.el6_5.x86_64
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
mod_nss-1.0.8-18.el6.x86_64 has missing requires of httpd >= ('0', '2.2.15', '24')
Your transaction was saved, rerun it with: yum load-transaction /tmp/yum_save_tx-2014-04-09-15-30rUVyRk.yumtx
然后我安装mod_nss-1.0.8-19.el6_5.x86_64时，报这个错误：
error: Failed dependencies:
httpd >= 2.2.15-24 is needed by mod_nss-1.0.8-19.el6_5.x86_64
怎么解决啊？
