I've been using drush with xdebug for years. It looks like it broke in the last two weeks, possibly due to modifications made to the core "drush" script (Split 'drush' script into finder, wrapper and launcher stages.). It now dispatches via "pcntl_exec" on Ubuntu, and xdebug never gets control back thereafter.
I've tried reverting drush to the previous commit ("8ab7ad9... Make uli test more resiliant vis-a-vis html tags that may be injected into log messages."), which fixes the xdebug problem, but does not appear to be compatible with RC1 :-(. So I strongly suspect the addition of pcntl_exec.
Anyone know how to get around this, or do I need to log an issue against drush on their github site?