A bug that only appears on one branch is expensive to reproduce when reproducing it means a vhost, an Apache restart and a line in /etc/hosts. PHP 5.4 added a single-process web server to the CLI binary, which reduces all of that to one command run in the directory you just checked out.
$ php -S 127.0.0.1:8000 -t public/
PHP 5.5.5 Development Server started at Thu Oct 31 09:12:44 2013
Listening on http://127.0.0.1:8000
Document root is /home/dev/catalogue/public
Press Ctrl-C to quit.
# a front controller, since there is no mod_rewrite here
$ php -S 127.0.0.1:8000 -t public/ public/router.phpThe router script is the only substitute for rewrite rules, and it has one rule of its own: return false for any path that exists on disk, or the front controller serves the stylesheets too. The reason this is a debugging tool rather than a development server is that it handles one request at a time — a page that fetches its own sidebar over HTTP deadlocks against itself, and so does anything waiting on a slow asset. No .htaccess, no process manager, no concurrency: that is the complete list of reasons never to let anything outside the machine reach it.