[CMake] Debugging the ExternalProject_Add download step

[Lori Pritchett-Sheats]

I'm using the ExternalProject_Add function and I've run into a problem 
downloading a tar file. It creates a zero length file and fails when the 
MD5 check fails. I have logging active, but I'm not seeing anything 
useful. I have other tar files from external sites that are downloaded 
successfully, so I don't know why this particular site is failing. The 
one difference is this site is a 'https://....' and the others are 
'http://...'.

How can I debug this problem? Is there an issue with the downloads and 
https?

Thanks.

-- 
Lori A. Pritchett-Sheats, PhD.
CCS-2, Computational Physics and Methods
Office: 505-665-6675
Fax: 505-665-4972

Los Alamos National Laboratory
P.O. Box 1663
MS D413
Los Alamos, NM 87544