XSPEC 12.15.1 and the "latest" APEC/NEI/SPEX versions

XSPEC 12.15.1 now supports the use of latest for APEC, NEI, and SPEX versions. If you start XSPEC 12.15.1 or later then your XSpec configuration file may contain this setting: for example

unix% grep VERSION ~/.xspec/Xspec.init
grep VERSION ~/.xspec/Xspec.init
ATOMDB_VERSION:  latest
SPEX_VERSION:  latest
NEI_VERSION: latest

Unfortunately the initialization code in XSPEC used by Sherpa (which is from a version earlier than 12.15.1) does not support this feature, which will result in output like

sherpa> plot_fit()
Reading APEC data from latest

Failed to read continuum data from latest_coco.fits
Failed to read latest_coco.fits
***calcMultiTempPlasma : failure in calcCIESpectrum, status = 1

and the model will evaluate to zero for each bin.

The only way to handle this is to either

delete the ~/.xspec/Xspec.init file,
or to edit the XXX_VERSION lines in this file to use the correct values.

The versions supported in CIAO 4.17 are:

ATOMDB_VERSION: 3.0.9
SPEX_VERSION: 3.0.7
NEI_VERSION: 3.0.9