credential: make relevance of http path configurable

When parsing a URL into a credential struct, we carefully record each part of the URL, including the path on the remote host, and use the result as part of the credential context. This had two practical implications: 1. Credential helpers which store a credential for later access are likely to use the "path" portion as part of the storage key. That means that a request to https://example.com/foo.git would not use the same credential that was stored in an earlier request for: https://example.com/bar.git 2. The prompt shown to the user includes all relevant context, including the path. In most cases, however, users will have a single password per host. The behavior in (1) will be inconvenient, and the prompt in (2) will be overly long. This patch introduces a config option to toggle the relevance of http paths. When turned on, we use the path as before. When turned off, we drop the path component from the context: helpers don't see it, and it does not appear in the prompt. This is nothing you couldn't do with a clever credential helper at the start of your stack, like: [credential "http://"] helper = "!f() { grep -v ^path= ; }; f" helper = your_real_helper But doing this: [credential] useHttpPath = false is way easier and more readable. Furthermore, since most users will want the "off" behavior, that is the new default. Users who want it "on" can set the variable (either for all credentials, or just for a subset using credential.*.useHttpPath). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>