Modified files.rb to handle tar error
Modified files.rb to handle tar error

Changed the run_pipeline! function to instead use Open3.pipeline_start
In doing so, the code is able to grab the last STDERR. In the case
where the error is the one from older tar versions (relating to ./),
it will not raise a Backup::Error. All other instances of command
failure will result in Backup::Error being raised.

stoplightio/gitlabhq,axilleas/gitlabhq,mmkassem/gitlabhq,axilleas/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq,iiet/iiet-git,iiet/iiet-git,mmkassem/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq