Intermittent failure fetching ReadTheDocs URL

gistfile1.txt

(h)  ~/h/r/h > curl -I 'https://h.readthedocs.io/en/latest/api/'
HTTP/1.1 200 OK
Server: nginx/1.10.0 (Ubuntu)
Date: Tue, 13 Jun 2017 13:20:52 GMT
Content-Type: text/html
Content-Length: 326
Last-Modified: Mon, 05 Jun 2017 09:11:35 GMT
Connection: keep-alive
Vary: Accept-Encoding
ETag: "59352047-146"
X-Subdomain-TryFiles: True
X-Served: Nginx
X-Deity: web03
Accept-Ranges: bytes

(h)  ~/h/r/h > curl -I 'https://h.readthedocs.io/en/latest/api/'
HTTP/1.1 200 OK
Server: nginx/1.10.0 (Ubuntu)
Date: Tue, 13 Jun 2017 13:20:53 GMT
Content-Type: text/html
Content-Length: 326
Last-Modified: Mon, 05 Jun 2017 09:11:35 GMT
Connection: keep-alive
Vary: Accept-Encoding
ETag: "59352047-146"
X-Subdomain-TryFiles: True
X-Served: Nginx
X-Deity: web03
Accept-Ranges: bytes

(h)  ~/h/r/h > curl -I 'https://h.readthedocs.io/en/latest/api/'
HTTP/1.1 200 OK
Server: nginx/1.10.0 (Ubuntu)
Date: Tue, 13 Jun 2017 13:20:54 GMT
Content-Type: text/html
Content-Length: 326
Last-Modified: Mon, 05 Jun 2017 09:11:35 GMT
Connection: keep-alive
Vary: Accept-Encoding
ETag: "59352047-146"
X-Subdomain-TryFiles: True
X-Served: Nginx
X-Deity: web03
Accept-Ranges: bytes

(h)  ~/h/r/h > curl -I 'https://h.readthedocs.io/en/latest/api/'
HTTP/1.1 404 Not Found
Server: nginx/1.10.0 (Ubuntu)
Vary: Accept-Encoding
Vary: Cookie, Accept-Language
Content-Type: text/html; charset=utf-8
Date: Tue, 13 Jun 2017 13:20:56 GMT
Transfer-Encoding: chunked
Content-Language: en
Connection: Keep-Alive
Set-Cookie: csrftoken=g4i5e7NZT7zZa88gaki2x5AMffAj7ALh; expires=Tue, 12-Jun-2018 13:20:56 GMT; httponly; Max-Age=31449600; Path=/