EAGLE_50 gravity + SPH problems

Currently the EAGLE_50 test will run on COSMA6 with self gravity and SPH enabled for a large number of steps (seen ~10500 and ~6500) and then exits with:

[0004] [18467.4] runner_doiact_grav.h:runner_dopair_grav_mm():159: Undrifted multipole

This is with debugging checks enabled.

The SLURM script is:

#!/bin/bash -l
#
# Batch script for bash users
#
#SBATCH --ntasks-per-node 1
#SBATCH --nodes 6
#SBATCH -J SWIFT-mpi-test
#SBATCH -o job.%J.dump
#SBATCH -e job.%J.err
#SBATCH -p cosma6
#SBATCH -A dp004
#SBATCH --exclusive
#SBATCH -t 600

module purge
module load swift
module load swift/c5/intel/intelmpi/2017-parallel

unset I_MPI_HYDRA_BOOTSTRAP

mpirun -np 6 ../swift_mpi -a -G -s -t 16 eagle_50.yml -v 1 

and configure options:

./configure --with-metis --enable-debug --enable-debugging-checks