Merge branch 'jk/http-error-messages'

Improve error reporting from the http transfer clients. * jk/http-error-messages: http: drop http_error function remote-curl: die directly with http error messages http: re-word http error message http: simplify http_error helper function remote-curl: consistently report repo url for http errors remote-curl: always show friendlier 404 message remote-curl: let servers override http 404 advice remote-curl: show server content on http errors http: add HTTP_KEEP_ERROR option