Remove bug.py. This is something I sent to Guido via email in or before

'94, demonstrating a thread bug that was later repaired via Python growing
an internal import lock.  It's of no current interest, and the now-std
test_threaded_import.py is pretty much the same test.

Demo/threads/README

@@ -3,7 +3,6 @@ This directory contains some demonstrations of the thread module.
 These are mostly "proof of concept" type applications:
 
 Generator.py	Generator class implemented with threads.
-bug.py		Demonstrate a bug with importing modules in threads.
 find.py		Parallelized "find(1)" (looks for directories).
 sync.py		Condition variables primitives by Tim Peters.
 telnet.py	Version of ../sockets/telnet.py using threads.

Demo/threads/bug.py

-# The following self-contained little program usually freezes with most
-# threads reporting
-#
-# Unhandled exception in thread:
-# Traceback (innermost last):
-#   File "importbug.py", line 6
-#     x = whrandom.randint(1,3)
-# AttributeError: randint
-#
-# Here's the program; it doesn't use anything from the attached module:
-
-import thread
-
-def task():
-    global N
-    import whrandom
-    x = whrandom.randint(1,3)
-    a.acquire()
-    N = N - 1
-    if N == 0: done.release()
-    a.release()
-
-a = thread.allocate_lock()
-done = thread.allocate_lock()
-N = 10
-
-done.acquire()
-for i in range(N):
-    thread.start_new_thread(task, ())
-done.acquire()
-print 'done'
-
-
-# Sticking an acquire/release pair around the 'import' statement makes the
-# problem go away.
-#
-# I believe that what happens is:
-#
-# 1) The first thread to hit the import atomically reaches, and executes
-#    most of, get_module.  In particular, it finds Lib/whrandom.pyc,
-#    installs its name in sys.modules, and executes
-#
-#         v = eval_code(co, d, d, d, (object *)NULL);
-#
-#    to initialize the module.
-#
-# 2) eval_code "ticker"-slices the 1st thread out, and gives another thread
-#    a chance.  When this 2nd thread hits the same 'import', import_module
-#    finds 'whrandom' in sys.modules, so just proceeds.
-#
-# 3) But the 1st thread is still "in the middle" of executing whrandom.pyc.
-#    So the 2nd thread has a good chance of trying to look up 'randint'
-#    before the 1st thread has placed it in whrandom's dict.
-#
-# 4) The more threads there are, the more likely that at least one of them
-#    will do this before the 1st thread finishes the import work.
-#
-# If that's right, a perhaps not-too-bad workaround would be to introduce a
-# static "you can't interrupt this thread" flag in ceval.c, check it before
-# giving up interpreter_lock, and have IMPORT_NAME set it & restore (plain
-# clearing would not work) it around its call to import_module.  To its
-# credit, there's something wonderfully perverse about fixing a race via an
-# unprotected static <grin>.
-#
-# as-with-most-other-things-(pseudo-)parallel-programming's-more-fun-
-#    in-python-too!-ly y'rs  - tim
-#
-# Tim Peters   tim@ksr.com
-# not speaking for Kendall Square Research Corp