Preproc writing wrong fibermap file

[parfa30]

This was noticed because OBJTYPE is not being identified properly in NightWatch. That's because the correct fibermap info is not being saved in the nightwatch files. I traced this to desispec.scripts.preproc. Line 161, sets the fibermapfile is fibermapfile = infile.replace('desi-', 'fibermap-').replace('.fits.fz', '.fits') but the fibermap file should really be fiberassign-.fits.fz. This is sent to io.readraw which sets it as an empty fibermap on line 144: fibermap = desispec.io.empty_fibermap(5000)