Dropbox returns 405 often on HEAD requests

I maintain some software that ingests files from dropbox. Recently it has started failing because dropbox often returns a 405 "Method not allowed" error on HEAD operations. Is this a known issue, is there a fix pending for this? 

 

Here's an example of this. (I have deleted this file but you can reproduce with pretty much any file in dropbox)

 

 

 

 

% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 302 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 302 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 302 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 405 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 302 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 302 
% curl -s  -I "https://www.dropbox.com/s/0f8gimqdxyid48e/test.txt?dl=1" | grep "HTTP"
HTTP/2 405