I ran into a group who would have benefited from #5899. However, since that is not yet possible, they tried to set two different directories for different versions of Astropy to run in parallel on the same file system on the same cluster. Otherwise, they run into a problem of astropy.cfg getting corrupted by the parallel attempts to write it.

Despite instructions at http://astropy.readthedocs.io/en/latest/config/index.html that says, "... if you’ve set the environment variable XDG_CONFIG_HOME and the $XDG_CONFIG_HOME/astropy directory exists, it will instead be there," they set XDG_CONFIG_HOME that included the "astropy" sub-directory. As a result, the check for $XDG_CONFIG_HOME/astropy failed (because it was really looking for $XDG_CONFIG_HOME/astropy/astropy) and fell back silently to the default ~/.astropy/config, which caused a lot of confusion.

Suggestion: If XDG_CONFIG_HOME is defined but the desired directory is not found, raise an exception (too much?) or at least emit a warning.