Registration fails ( "Error creating new registration" 500 ) when email address has a - in it

I attempted to use the letsencrypt CLI tool to create a certificate, using an email address with a - in it. It failed consistently 3 times with the following error:

2015-11-26 22:14:24,082:DEBUG:acme.client:Received response <Response [500]> (headers: {‘Content-Length’: ‘96’, ‘Expires’: ‘Fri, 04 Dec 2015 10:30:34 GMT’, ‘Server’: ‘nginx’, ‘Connection’: ‘close’, ‘Pragma’: ‘no-cache’, ‘Cache-Control’: ‘max-age=0, no-cache, no-store’, ‘Date’: ‘Fri, 04 Dec 2015 10:30:34 GMT’, ‘Content-Type’: ‘application/problem+json’, ‘Replay-Nonce’: ‘6tnCEY7xHN9tFsSpM25CjHEt4N1r2ebVfX9QS4ifGrs’}): ‘{“type”:“urn:acme:error:serverInternal”,“detail”:“Error creating new registration”,“status”:500}’

When I switched to an alias email address that didn’t have a - in it, it worked first time.