Bug 1910923

Description of problem:
python3-z3 doesn't work on a clean Fedora 33.

Version-Release number of selected component (if applicable):
4.8.9-3.fc33

How reproducible:
Always

Steps to Reproduce:
1. Start with a fresh Fedora (I used a container: `podman run -it fedora:33`)

2. In the container install python3-z3: `dnf install python3-z3`

3. Try to use z3: `python3 -c 'import z3'`. You'll encounter the first problem:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.9/site-packages/z3/__init__.py", line 1, in <module>
    from .z3 import *
  File "/usr/lib/python3.9/site-packages/z3/z3.py", line 43, in <module>
    from . import z3core
  File "/usr/lib/python3.9/site-packages/z3/z3core.py", line 5, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

It means that python3-z3 requires python3-setuptools as a dependency, but it's not there.

4. Fix the dependency issue manually: `dnf install python3-setuptools`

5. Try to use z3 again: `python3 -c 'import z3'`. You'll encounter the second problem:

Could not find libz3.so; consider adding the directory containing it to
  - your system's PATH environment variable,
  - the Z3_LIBRARY_PATH environment variable, or 
  - to the custom Z3_LIBRARY_DIRS Python-builtin before importing the z3 module, e.g. via
    import builtins
    builtins.Z3_LIB_DIRS = [ '/path/to/libz3.so' ] 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.9/site-packages/z3/__init__.py", line 1, in <module>
    from .z3 import *
  File "/usr/lib/python3.9/site-packages/z3/z3.py", line 43, in <module>
    from . import z3core
  File "/usr/lib/python3.9/site-packages/z3/z3core.py", line 67, in <module>
    raise Z3Exception("libz3.%s not found." % _ext)
z3.z3types.Z3Exception: libz3.so not found.

Actual results:
You cannot import and start using z3 successfully in Python 3.


Expected results:
`python3 -c 'import z3'` exits without error.

Additional info:
I think the first problem can be solved by adding python3-setuptools to the .spec file on line 82:
https://src.fedoraproject.org/rpms/z3/blob/259befebd79b14f80baef3ce4bd8dbdf12d253ce/f/z3.spec#_82

The second problem happens because z3 looks for libz3.so but Fedora install the shared object under /usr/lib64/libz3.so.4.8. Therefore /usr/lib64/libz3.so doesn't exists and z3 fails to load.

A temporary workaround is symlinking the shared object: `ln -s libz3.so.4.8 /usr/lib64/libz3.so`

(The code in z3 that looks for the SO is in https://github.com/Z3Prover/z3/blob/7f0b5bc129988225c831314202608a26a18170f9/scripts/update_api.py#L1804)

I'm available if you need any clarifications or assistance :)
Best,
Nik