[Pythonmac-SIG] does pkg_resources think that "macosx-10.3" is incompatible with 10.5?

[zooko]

Folks:

It appears that eggs built on Mac OS 10.4 are produced with filenames  
containing "macosx-10.3", like this:

http://pypi.python.org/packages/2.5/s/simplejson/simplejson-1.7.3- 
py2.5-macosx-10.3-fat.egg

but that if you try to easy_install such a package on Mac OS 10.5, it  
will deem that egg to be incompatible with the current platform and  
will instead try to install from a source tarball if it can find  
one.  (On the other hand if you install that egg on Mac OS 10.4, it  
will work.)

PJE reports that the platform versioning code for OS X was  
contributed by someone other than he to pkg_resources, and that he  
doesn't know how it works, except that it reads /usr/bin/sw_vers.

Does anyone know if there is a good reason for Python running on 10.5  
to reject binaries built on 10.4, and if not what would be required  
to make this version check pass?

Here is a ticket on the allmydata.org tahoe project about this issue:

http://allmydata.org/trac/tahoe/ticket/212

(Tahoe is a new distributed, cryptographically protected filesystem.   
It's super cool.  Check it out.)

Thanks!

Regards,

Zooko