Run any shell command inside Quibble test env
To generate per patch code coverage, all built-in test commands should
be skipped and replaced by arbitrary shell commands. Eg:
cd extensions/Foobar phpunit-patch-coverage check \ --command "php -d zend_extension=xdebug.so ../../tests/phpunit/phpunit.php" \ --html /tmp/coverage-Foobar.html
I still need Quibble to do the installation and spawn the backends. But
built-in commands should be skip entirely (--skip=all).
Add a '--user-commands' switch that lets one execute shell commands
AFTER all stages have been run. Each is run in its own shell relatively
to MediaWiki installation path.