How to interpret "Connection: keep-alive, close"?

From what I understand, an HTTP connection could either be keep-alive or close.

I sent an HTTP request to a server:

GET /page1/ HTTP/1.1
Host: server.com
Connection: keep-alive

And it responded with:

HTTP/1.1 200 OK
Connection: keep-alive, close

Essentially, I believe the server is bugged because a response like keep-alive, close is ambiguous.

However, as the receiver, how should we handle such a message? Should we interpret this header value as keep-alive or close?