While building pywin32 with Py3k trunk (not release version), I get this 
traceback:

   Creating library build\temp.win32-
3.1\Release\win32\src\pywintypes31.lib and object buil
d\temp.win32-3.1\Release\win32\src\pywintypes31.exp
Traceback (most recent call last):
  File "setup3.py", line 16, in <module>
    exec(str(got))
...skipping...
  File "<string>", line 2194, in <module>
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\core.py", line 149, in setup
    dist.run_commands()
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\dist.py", line 919, in run_commands
    self.run_command(cmd)
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\dist.py", line 938, in run_command
    cmd_obj.run()
  File "<string>", line 619, in run
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\command\build.py", line 128, in run
    self.run_command(cmd_name)
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\cmd.py", line 315, in run_command
    self.distribution.run_command(command)
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\dist.py", line 938, in run_command
    cmd_obj.run()
  File 
"C:\HOME\as\apy\branches\nightly\build\pyhg_branches_release3_1_maint-
win32-x86-hgti
\command\build_ext.py", line 347, in run
p31-rrun\python\lib\distutils\ccompiler.py", line 791, in 
link_shared_object
    extra_preargs, extra_postargs, build_temp, target_lang)
  File "<string>", line 1384, in link
p31-rrun\python\lib\distutils\msvc9compiler.py", line 663, in link
    manifest_buf = re.sub(pattern, "", manifest_buf)
p31-rrun\python\lib\re.py", line 166, in sub
    return _compile(pattern, flags).sub(repl, string, count)
TypeError: can't use a string pattern on a bytes-like object