I guess this is a bug in SCons that it fails when “files” are actually directories. These directories aren’t empty (as it was for one of the links you pointed us to). But I think earlier versions of SCons didn’t recursively install the files in the directory. I forget if it just wrote an empty directory or didn’t do anything with directories.
So to install the subdirectories, I added explicit install commands for the three subdirectories. It looks like a solution here that doesn’t involve hacking SCons would be to add the lines
files.remove('SEDs') files.remove('bandpasses') files.remove('sensors')
glob.glob('*') line in share/SConscript in GalSim.
I can do this on the releases/1.5 branch and cut a new GalSim 1.5.3 if that would be helpful. Of course, there are now version 1.6 and 2.0, so I’m not sure if it is better to just do this on those branches and upgrade to one of those.