pipefail is a bashism

so set it only when /bin/sh points to a bash
debian: copy logrotation file after make

because at configure stage its not yet created

Signed-off-by: Sven Nierlein <sven@consol.de>
add conflicts to pure thruk pkg

because we use the same folders for various files

Signed-off-by: Sven Nierlein <sven@consol.de>