Comment 5 for bug 520715

I don't have a test suite for other ruby libs, so no I can't say with certainty that building them without pthreads doesn't break them, but being the default for usptream ruby, and used by Red Hat leads me to believe that ruby without pthreads has been pretty thoroughly tested elsewhere.

I'm pretty sure it's a ruby bug. installing an older version of ruby from Karmic allowed puppet to work fine. You can see in the ruby bug I linked that I was able to find the specific upstream change, which was related to threading, where the problem began. And I've been able to reliably run puppet without problems by disabling pthreads in the current version.

For convenience, here's the upstream change where the badness started happening:
http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=24104
And the file diff of what changed:
http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/branches/ruby_1_8_7/eval.c?r1=23997&r2=24104&diff_format=h