Merge branch 'bc/http-empty-auth'

Some authentication methods do not need username or password, but
libcurl needs some hint that it needs to perform authentication.
Supplying an empty username and password string is a valid way to
do so, but you can set the http.[<url>.]emptyAuth configuration
variable to achieve the same, if you find it cleaner.

* bc/http-empty-auth:
http: add option to try authentication without username

diff --cc Documentation/config.txt
index 01cca0a70177091f4580a06ea53e498d3e5be4e4,d9abfbb4277ac93b5697ccd2e8299c8c5d17ae66..542cb229c86415aeb338814c2caf4e746d3c33f5
--- 1/Documentation/config.txt
--- 2/Documentation/config.txt
+++ b/Documentation/config.txt
@@@ -1619,35 -1596,16 +1619,41 @@@ help.htmlPath:
  
  http.proxy::
        Override the HTTP proxy, normally configured using the 'http_proxy',
 -      'https_proxy', and 'all_proxy' environment variables (see
 -      `curl(1)`).  This can be overridden on a per-remote basis; see
 -      remote.<name>.proxy
 +      'https_proxy', and 'all_proxy' environment variables (see `curl(1)`). In
 +      addition to the syntax understood by curl, it is possible to specify a
 +      proxy string with a user name but no password, in which case git will
 +      attempt to acquire one in the same way it does for other credentials. See
 +      linkgit:gitcredentials[7] for more information. The syntax thus is
 +      '[protocol://][user[:password]@]proxyhost[:port]'. This can be overridden
 +      on a per-remote basis; see remote.<name>.proxy
 +
 +http.proxyAuthMethod::
 +      Set the method with which to authenticate against the HTTP proxy. This
 +      only takes effect if the configured proxy string contains a user name part
 +      (i.e. is of the form 'user@host' or 'user@host:port'). This can be
 +      overridden on a per-remote basis; see `remote.<name>.proxyAuthMethod`.
 +      Both can be overridden by the 'GIT_HTTP_PROXY_AUTHMETHOD' environment
 +      variable.  Possible values are:
 ++
 +--
 +* `anyauth` - Automatically pick a suitable authentication method. It is
 +  assumed that the proxy answers an unauthenticated request with a 407
 +  status code and one or more Proxy-authenticate headers with supported
 +  authentication methods. This is the default.
 +* `basic` - HTTP Basic authentication
 +* `digest` - HTTP Digest authentication; this prevents the password from being
 +  transmitted to the proxy in clear text
 +* `negotiate` - GSS-Negotiate authentication (compare the --negotiate option
 +  of `curl(1)`)
 +* `ntlm` - NTLM authentication (compare the --ntlm option of `curl(1)`)
 +--
  
+ http.emptyAuth::
+       Attempt authentication without seeking a username or password.  This
+       can be used to attempt GSS-Negotiate authentication without specifying
+       a username in the URL, as libcurl normally requires a username for
+       authentication.
+ 
  http.cookieFile::
        File containing previously stored cookie lines which should be used
        in the Git http session, if they match the server. The file format

diff --cc http.c
Simple merge