[...]

r has empty body
error: Macro %_builddir has empty body
Executing(--clean): env -i TMP=/home/users/builder/tmp HOME=/home/users/builder PATH=/bin:/usr/bin:/usr/sbin:/sbin:/usr/X11R6/bin TMPDIR=/home/users/builder/tmp  /bin/sh -e /home/users/builder/tmp/rpm-tmp.51049
+ umask 022
+ cd /home/users/builder/rpm/BUILD
+ rm -rf kernel-4.14-vanilla-4.14.108
Begin-TLD-Builder-Info
Build-Time: user:4.71s sys:0.66s real:22.10s (faults io:127 non-io:157204)
Files queued for ftp:
 103281505 kernel-4.14-vanilla-4.14.108-1.src.rpm
       200 kernel-4.14-vanilla-4.14.108-1.src.rpm.uploadinfo
End-TLD-Builder-Info