python3.7 installation failing - so why?

[Frank Miles]

On Sat, 23 Feb 2019 14:56:03 +1100, Chris Angelico wrote:

> On Sat, Feb 23, 2019 at 2:51 PM Frank Miles <pedicularis at mail.com>
> wrote:
>>
>> I have a Debian/Linux machine that I just upgraded to the newer
>> "testing"
>> distribution.  I'd done that earlier to another machine and all went
>> well.  With the latest machine, python2 is OK but python3 can barely
>> run at all.  For example:
>>
>> $ python3 Python 3.7.2+ (default, Feb  2 2019, 14:31:48)
>> [GCC 8.2.0] on linux Type "help", "copyright", "credits" or "license"
>> for more information.
>> >>> help()
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>>   File "/usr/lib/python3.7/_sitebuiltins.py", line 102, in __call__
>>     import pydoc
>>   File "/usr/lib/python3.7/pydoc.py", line 66, in <module>
>>     import inspect
>>   File "/usr/lib/python3.7/inspect.py", line 40, in <module>
>>     import linecache
>>   File "/usr/lib/python3.7/linecache.py", line 11, in <module>
>>     import tokenize
>>   File "/usr/lib/python3.7/tokenize.py", line 33, in <module>
>>     import re
>>   File "/usr/lib/python3.7/re.py", line 143, in <module>
>>     class RegexFlag(enum.IntFlag):
>> AttributeError: module 'enum' has no attribute 'IntFlag'
>> >>>
>> >>>
>> Question: how can I determine what has gone wrong?
> 
> Hmm. I'd start with:
> 
> $ which python3 $ dpkg -S `which python3`
> 
> and from inside Python:
>>>> import sys; sys.path import enum; enum.__file__
> 
> My best guess at the moment is that your "enum" package is actually a
> compatibility shim for earlier Python versions, less functional than the
> one provided by Python 3.7. You may need to *uninstall* a shim package.
> But I could well be wrong, and maybe there'd be a clue in your paths.
> 
> ChrisA

Whoopee!  You nailed it!
The path included /usr/local/lib/python3.7/dist-packages, which included
an enum file as you suggested.  The 'import enum; enum.__file__' (gonna
have to look up that syntax) provided with the path to that directory.

Many thanks Chris for a most helpful suggestion!
   -Frank