If I try to build a bdist_msi installer for a trivial
module, using Python 2.5b1, I get an error.

It looks like a problem with the interaction of the new
(in 2.5) egg-info stuff and the bdist_msi code - but I
have no further ideas.
Here is the setup.py

from distutils.core import setup
setup(
   name='test',
   version='1.0',
   py_modules=['test'],
)

And here is the build output:

>python setup.py bdist_msi
running bdist_msi
running build
running build_py
creating build
creating build\lib
copying test.py -> build\lib
installing to build\bdist.win32\msi
running install_lib
creating build\bdist.win32
creating build\bdist.win32\msi
creating build\bdist.win32\msi\Lib
creating build\bdist.win32\msi\Lib\site-packages
copying build\lib\test.py ->
build\bdist.win32\msi\Lib\site-packages
running install_egg_info
Writing
build\bdist.win32\msi\Lib\site-packages\test-1.0-py2.5.egg-info
creating dist
Traceback (most recent call last):
 File "setup.py", line 5, in <module>
   py_modules=['test'],
 File "D:\Apps\Python25\Lib\distutils\core.py", line
151, in setup
   dist.run_commands()
 File "D:\Apps\Python25\Lib\distutils\dist.py", line
974, in run_commands
   self.run_command(cmd)
 File "D:\Apps\Python25\Lib\distutils\dist.py", line
994, in run_command
   cmd_obj.run()
 File
"D:\Apps\Python25\Lib\distutils\command\bdist_msi.py",
line 235, in run
   self.add_files()
 File
"D:\Apps\Python25\Lib\distutils\command\bdist_msi.py", line
263, in add_files
   key = dir.add_file(file)
 File "D:\Apps\Python25\Lib\msilib\__init__.py", line
343, in add_file
   language, attributes, sequence)])
 File "D:\Apps\Python25\Lib\msilib\__init__.py", line
115, in add_data
   raise MSIError("Could not insert "+repr(values)+"
into "+table)
_msi.MSIError: Could not insert [(None, 'site_packages',
'TEST-1~1.EGG|test-1.0-py2.5.egg-info', 186L, None,
None, 512, 1)]
into File

Logged In: YES 
user_id=21627

Thanks for the report. This is now fixed in r47280.