Show usage string for 'git http-push -h'

http-push already knows how to dump usage if it is given no options, but
it interprets '-h' as the URL to a remote repository:

    $ git http-push -h
    error: Cannot access URL -h/, return code 6

Dump usage instead.  Humans wanting to pass the URL -h/ to curl for some
reason can use 'git http-push -h/' explicitly.  Scripts expecting to
access an HTTP repository at URL '-h' will break, though.

Also delay finding a git directory until after option parsing, so
"http-push -h" can be used outside any git repository.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -1792,8 +1792,6 @@ int main(int argc, char **argv)
 
 	git_extract_argv0_path(argv[0]);
 
-	setup_git_directory();
-
 	repo = xcalloc(sizeof(*repo), 1);
 
 	argv++;
@@ -1827,6 +1825,8 @@ int main(int argc, char **argv)
 				force_delete = 1;
 				continue;
 			}
+			if (!strcmp(arg, "-h"))
+				usage(http_push_usage);
 		}
 		if (!repo->url) {
 			char *path = strstr(arg, "//");
@@ -1854,6 +1854,8 @@ int main(int argc, char **argv)
 	if (delete_branch && nr_refspec != 1)
 		die("You must specify only one branch name when deleting a remote branch");
 
+	setup_git_directory();
+
 	memset(remote_dir_exists, -1, 256);
 
 	/*