mympirun cannot be used to start mpi shells (as STDOPEN and STDIN are seem to be closed)

[hajgato]

cp2k_shell.psmp is a cp2k shell and some software (for example ASE) uses it to control CP2K calculations, etc. Therefore, it should be opened with mpirun, and it accepts commands as it would be a shell. If we start with simply mpirun, the shell works, if we start with mympirun, then it gets an empty stdin, and immediately closes. See https://otrsdict.ugent.be/otrs/index.pl?Action=AgentTicketZoom;TicketID=78625

The users claims that it used to work before, but I tried 2 previous versions (5.2.9, and 5.2.10) and they have the same behavior as 5.2.11.
Not sure that this behavior is opsystem dependent or not, but I guess it should be.