Cannot wait for conditions when threads are disabled

Imported from https://youtrack.roxen.com/issue/PIKE-18

Reported by Marcus Wellhardh wellhard@roxen.com

After a thread dump the following error is repeated all over until the server restarted by the ABS:

11:13:53            : Internal server error: Cannot wait for conditions when threads are disabled!
-:1: Thread.Queue(0)->wait(_static_modules.Builtin()->mutex_key())
pike/lib/modules/Thread.pmod:275: Thread.Queue(0)->read()
base_server/roxen.pike (cf814f9c):715: roxen()->handler_thread(4)
```
See attachment for more info.

The entire log is in /home/wellhard/Kunder/Shaw/default.2.bz2

#### Attachments:

- [dump.txt](/uploads/b3aecbad5761f3f1b325481da2c98a8b/dump.txt "dump.txt")