+# die_error(<http_status_code>, <error_message>)
+# Example: die_error(404, 'Hash not found')
+# By convention, use the following status codes (as defined in RFC 2616):
+# 400: Invalid or missing CGI parameters, or
+# requested object exists but has wrong type.
+# 403: Requested feature (like "pickaxe" or "snapshot") not enabled on
+# this server or project.
+# 404: Requested object/revision/project doesn't exist.
+# 500: The server isn't configured properly, or
+# an internal error occurred (e.g. failed assertions caused by bugs), or
+# an unknown error occurred (e.g. the git binary died unexpectedly).