Hi,

Attached is the patch I used for trying to update python 3 to 3.5. I disabled 
a test and added an exception handler for some code calling pwd.getpwuid(0) 
and the group equivalent.

It builds outside of the python.scm module but if I change the version in 
python.scm python-minimal ends up with a link error.

*** WARNING: renaming "_ctypes" since importing it failed: build/lib.linux-
x86_64-3.5/_ctypes.cpython-35m-x86_64-linux-gnu.so: cannot open shared object 
file: No such file or directory
error: [Errno 2] No such file or directory: 'build/lib.linux-
x86_64-3.5/_ctypes.cpython-35m-x86_64-linux-gnu.so' -> 'build/lib.linux-
x86_64-3.5/_ctypes.cpython-35m-x86_64-linux-gnu_failed.so'
Makefile:608: recipe for target 'sharedmods' failed

I'm currently pretty baffled by the link error as if I do --keep-failed I can 
get it to build with:
cd /tmp/nix-builc-python-minimal-3.5.1.drv
chown -R me .
guix environment python-minimal
cd Python-3.5.1
make

Diane