`flappserver create` hangs forever

[Jean-Paul Calderone]

$ flappserver --version                                                           
Foolscap version: 0.12.4
Twisted version: 16.5.0
$ flappserver create --location localhost:3116 /tmp/hang-forever
Server Running
Foolscap Application Server created in /tmp/hang-forever
TubID 2xfl6tpzc4uozbyg7bl27tygg3zsgjpg, listening on port tcp:3116
Now launch the daemon with 'flappserver start /tmp/hang-forever'
<time passes>
^CUnhandled error in Deferred:

This seems to be because of the interaction between run_flappserver and the defer.succeed(0) returned by Create.run. The Deferred has already fired so the callbacks run immediately, including the reactor.stop(), then the reactor gets run afterwards - and nothing ever stops it.

[Brian Warner]

Fixed by exarkun's PR in [58f549ff6]. The long-term fix is to move to task.react, of course, but this is absolutely the right starting point.

[Brian Warner]

BTW, this was probably introduced in [ad5db04c], where flappserver creation became synchronous (that commit removed the d = fireEventually(), which was shielding us from the bug). So this was broken starting in foolscap-0.12.0 .