Under certain circumstances, creating a directory using os.mkdir then
immediately changing to it using os.chdir fails with a file not found
exception.

Here is some code to demonstrate that. Using the following program with
a parameter of 1 works fine. But anything greater than that and
exceptions occur in the first os.chdir until only one thread is left to
run completely.

Tested on Python 2.5.1 for Windows and Python 2.3.5 for Linux.

    # mkdirtest.py
    #
    # usage: mkdirtest <number of threads>

    import os, threading, sys

    x = int(sys.argv[1])

    class MkdirTest(threading.Thread):

        def __init__(self, t):
            threading.Thread.__init__(self)
            self.t = t
            print "new thread "+str(t)

        def run(self):
            for i in range(0,50):
                s = str(self.t)+"_"+str(i)
                print "mkdir "+s
                os.mkdir(s)
                os.chdir(s)
                os.chdir("..")
            print "end thread "+str(t)

    for t in range(0,x):
        print t
        a = MkdirTest(t)
        a.start()

This isn't a bug in Python.  Working directory, which os.chdir modifies,
is process-global.  One of your threads makes a directory, then gets
suspended while another one makes a different directory and changes into
it, then the first tries to change into its directory and fails.

Sorry for filing this as a bug, I am a fool. I should have read the
documentation for each operating systems' mkdir call more carefully.