Project: datamanagement
Issue DM-6664: Investigate why afw.table.IdFactory doesn't allow reserved=0
Setting reserved=0 when constructing a source ID factory (as would be logical when there is no exposure ID to reserve bits for) strangely doesn't work; it seems to be necessary to reserve at least one bit. This may be a signedness problem (we use signed 64-bit integers for IDs to appease FITS, which is unfortunate), but we should be careful just reducing the number of available bits, as this could break code that expect to read IDs already written to disk. Note that any change to this code in afw.table may require changes to code in daf.butlerUtils.ExposureIdInfo as well.
Story points: 2