Hello,

A build of mumps-openmpi with mpich fails:

guix time-machine -- build mumps-openmpi --with-input=openmpi=mpich

[...]
  mpirun -n 3 ./test_scotch_dgraph_check data/bump.grf
  Invalid error code (-2) (error ring index 127 invalid)
  INTERNAL ERROR: invalid error code fffffffe (Ring Index out of range) in MPID_nem_tcp_init:373
  Invalid error code (-2) (error ring index 127 invalid)
  INTERNAL ERROR: invalid error code fffffffe (Ring Index out of range) in MPID_nem_tcp_init:373
  Invalid error code (-2) (error ring index 127 invalid)
  INTERNAL ERROR: invalid error code fffffffe (Ring Index out of range) in MPID_nem_tcp_init:373
  Fatal error in PMPI_Init: Other MPI error, error stack:
  MPIR_Init_thread(586)..............: 
  MPID_Init(224).....................: channel initialization failed
  MPIDI_CH3_Init(105)................: 
  MPID_nem_init(324).................: 
  MPID_nem_tcp_init(175).............: 
  MPID_nem_tcp_get_business_card(401): 
  MPID_nem_tcp_init(373).............: gethostbyname failed, localhost (errno 0)


This is what Ludo reproduced: