FWIW, I just ran into the following on Solaris 10:

% dbx python
For information about new features see `help changes'
To remove this message, put `dbxenv suppress_startup_message 7.9' in your .dbxrc
Reading python
Reading ld.so.1
Reading libsocket.so.1
Reading libnsl.so.1
Reading libintl.so.1
Reading librt.so.1
Reading libdl.so.1
Reading libsendfile.so.1
Reading libm.so.2
Reading libthread.so.1
Reading libc.so.1
Reading libaio.so.1
Reading libmd.so.1
(dbx) run                                                                    
Running: python 
(process id 17819)
Reading libc_psr.so.1
Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Fatal Python error: Py_Initialize: Unable to get the locale encoding
Traceback (most recent call last):
  File "<frozen importlib._bootstrap>", line 1558, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1525, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 586, in _check_name_wrapper
  File "<frozen importlib._bootstrap>", line 1023, in load_module
  File "<frozen importlib._bootstrap>", line 1004, in load_module
  File "<frozen importlib._bootstrap>", line 562, in module_for_loader_wrapper
  File "<frozen importlib._bootstrap>", line 854, in _load_module
  File "<frozen importlib._bootstrap>", line 990, in get_code
  File "<frozen importlib._bootstrap>", line 1051, in _cache_bytecode
  File "<frozen importlib._bootstrap>", line 1065, in set_data
OSError: [Errno 30] Read-only file system: '/home/cpython/nfs/src/3.x/Lib/encodings/__pycache__'
t@1 (l@1) signal ABRT (Abort) in __lwp_kill at 0xffffffff7e2dc2c0
0xffffffff7e2dc2c0: __lwp_kill+0x0008:  bcc,a,pt  %icc,__lwp_kill+0x18  ! 0xffffffff7e2dc2d0
Current function is Py_FatalError
 2360       abort();
(dbx) q 
q: not found
(dbx) quit


Testing the 'import_error.diff' patch now...