Add pip fall-back installation for more exotic Linux distributions #2
Description
Using the 'pip' module of Ansible, one could possibly support a few more 'exotic' or older distributions, where rdiff-backup isn't packaged by default. It would probably require looping through the installation of (packaged) dependencies with varying names, ignoring errors and/or listing the correct dependencies for some platforms (python-devel, librsync-devel, gcc, etc...).
A variable should be defined to allow enforcing the pip installation, and another one to choose the version to install (rdiff-backup vs. rdiff-backup==<VERSION>).