I updated to cygwin 1.7.15 this afternoon and went to run the same nant script I ran successfully this morning, except that nant now hangs - no output is ever shown. I've verified nant (0.91.3881.0 alpha2) still runs in a windows cmd prompt and I've tried to rebaseall on cygwin without any luck.
Edit: In 1.7.15, nant doesn't show as a process in task manager nor Process Explorer (sysinternals).
How do I get nant back working in cygwin?
It looks like this is a known bug with a fix coming. There doesn't appear to be an ETA on the fix. You can work around it by reverting to Cygwin 1.7.14. Redirecting stderr and stdout doesn't work.
If you use "non-cygwin dlls" make sure you set the CYGWIN environment variable to pipe_byte (see here for more info).