Travis: Initiating build for commit '2133945ff60d3693fd55d727a45f67f38bb71564' on branch 'master': fixes  #6237 Reading php_uname in case shell_exec failed.
According to http://forum.piwik.org/read.php?2,113613,page=1#msg-113739
php_uname will not return full string as in the shell, so we must first read shell_exec output