Found it! There was a problem in the fstab entry which was responsible for mounting the partition. I was using *noexec* instead of *exec.* Just had to change this:
*/dev/vg0/jenkins /jenkins ext4 defaults,auto,noatime,noexec 0 0* * * for this: * * */dev/vg0/jenkins /jenkins ext4 defaults,auto,noatime,exec 0 0** * * * Living and learning! Thanks for everybody who tried to help!