Test for trialing slashes in value for 'issuer' from '/.well-known/openid-configuration' responses

Basically our ESS Brokers are advertising themselves (in their /.well-known/openid-configuration responses) as issuers with a trailing slash, e.g. for https://broker.pod.inrupt.com/.well-known/openid-configuration:

{
    "introspection_endpoint": "https://broker.pod.inrupt.com/introspect",
    "scopes_supported": [
        "openid",
        "offline_access",
        "webid"
    ],
    "issuer": "https://broker.pod.inrupt.com/",
    :

Note the trailing slash on the issuer URL (which is technically (slightly!) more correct than having the URL without the trailing slash).
So it seems NSS might be blindly taking that issuer value, and appending the string literal /.well-known/openid-configuration to it, without first checking if the issuer value has a trailing slash or not. If the URL constructed has two slashes, then the server responds with it’s standard HTML ‘Page Not Found’ response, which results in the ‘invalid json response…’ error.

If this is correct, then the fix in NSS should be simply checking for a trailing slash before appending /.well-known/openid-configuration.

首先找出根據 OpenID 設定回應中傳回的 issuer 建立 /.well-known/openid-configuration URL 的程式碼。為帶有和不帶結尾斜線的 issuer 值新增涵蓋範圍，並確認兩者都會產生只有一個斜線的有效 URL，而不是無效的 JSON 回應。