Something is still broken in port detach

[brson]

Just saw this log from the bots http://bot.rust-lang.org/logs/2012/02/06/2012-03-06T10:19:41Z-50cd8e15-3023-4ec6-afde-e627de1a0f2d.html

Related to the hack here: ee991ca

Ports are supposed to be completely dereffed before del_port but that isn't happening.

[brson]

This one might fix it: dc0b9f4

If no further issues show up for a few days then I'll close this.

[brson]

I believe this is fixed.