Não sei se foi o jeito certo de proceder, mas resolvi meu problema instalando repositório EPEL (Extra Packages for Enterprise Linux) :
$ sudo yum install epel-release
The EPEL repository is managed by the EPEL group, which is a Special Interest Group within the Fedora Project. The ‘EPEL’ part is an abbreviation that stands for Extra Packages for Enterprise Linux. The EPEL group creates, maintains and manages a high quality set of additional packages. These packages may be software not included in the core repository, or sometimes updates which haven’t been provided yet.
Source
E o pacote httplib2 está disponível:
$ sudo yum -y install python-pip