There is a stray warning message during the "make" process about a missing fsfilt-ldiskfs.c file:

Type 'make' to build Lustre.
+ make -j 2 -s
Making all in .
WARNING: could not open /var/lib/jenkins/workspace/lustre-reviews/arch/x86_64/build_type/server/distro/el6/ib_stack/inkernel/BUILD/BUILD/lustre-2.4.52/lustre/lvfs/fsfilt-ldiskfs.c: No such file or directory
Making all in libsysio

It does not appear to be a major problem, since compilation completes without any further trouble. But clearly something is not quite right in the build system and we should fix it when time permits.