[3.7] bpo-35028: cgi: Fix max_num_fields off by one error (GH-9973)#10053

miss-islington merged 1 commit intopython:3.7python/cpython:3.7from

miss-islington:backport-b79b5c0-3.7miss-islington/cpython:backport-b79b5c0-3.7Copy head branch name to clipboard