python: Normalize exceptions

The python 3 incompatible call of `file` in the python hook caused an
exception. Trying to get the traceback failed because the exception
isn't normalized:

13: [ RUN      ] Hooker.Ordering
13: paludis@1565848332: [WARNING hook.python.traceback_failed] In thread ID '13623':
13:   ... When triggering hook 'ordering':
13:   ... When running hook 'hooker_TEST_dir/ordering/py_hook.py' for hook 'ordering':
13:   ... When getting traceback
13:   ... Hook 'hooker_TEST_dir/ordering/py_hook.py': _get_traceback(): traceback.format_exception failed
13: paludis@1565848332: [WARNING hook.python.failure] Hook 'hooker_TEST_dir/ordering/py_hook.py': running hook_run_ordering function failed: 'Getting traceback failed'
13: paludis@1565848332: [WARNING hook.python.failure] Hook 'hooker_TEST_dir/ordering/py_hook.py' failed unexpectedly: 'Traceback (most recent call last):
13:   File "/usr/x86_64-pc-linux-gnu/lib/python3.7/traceback.py", line 121, in format_exception
13:     type(value), value, tb, limit=limit).format(chain=chain))
13:   File "/usr/x86_64-pc-linux-gnu/lib/python3.7/traceback.py", line 476, in __init__
13:     if (exc_value and exc_value.__cause__ is not None
13: AttributeError: 'str' object has no attribute '__cause__'
13:
13: The above exception was the direct cause of the following exception:
13:
13: Traceback (most recent call last):
13:   File "/home/marv/devel/paludis-worktrees/cross/python/paludis_output_wrapper.py", line 101, in restore_prefix
13:     restore("both")
13:   File "/home/marv/devel/paludis-worktrees/cross/python/paludis_output_wrapper.py", line 80, in restore
13:     if len(stderr_cache):
13: SystemError: <built-in function len> returned a result with an error set'
13: ../paludis/hooker_TEST.cc:76: Failure
13: Expected equality of these values:
13:   0
13:   result.max_exit_status()
13:     Which is: 1
13: ../paludis/hooker_TEST.cc:83: Failure
13: Expected equality of these values:
13:   "e\nc\nf\nd\nb\na\npy_hook\ng\ni\nh\nsohook\nk\nj\n"
13:   line
13:     Which is: "e\nc\nf\nd\nb\na\ng\ni\nh\nsohook\nk\nj\n"
13: With diff:
13: @@ -5,5 @@
13:  b
13:  a
13: -py_hook
13:  g
13:  i
13:
13: [  FAILED  ] Hooker.Ordering (195 ms)

1 files changed, 1 insertions, 0 deletions

diff --git a/paludis/python_hooks.cc b/paludis/python_hooks.cc
index e47fc7a58..566bd1ddc 100644
--- a/paludis/python_hooks.cc
+++ b/paludis/python_hooks.cc
@@ -393,6 +393,7 @@ PyHookFile::_get_traceback() const
 
     PyObject * ptype, * pvalue, * ptraceback;
     PyErr_Fetch(&ptype, &pvalue, &ptraceback);
+    PyErr_NormalizeException(&ptype, &pvalue, &ptraceback);
 
     if (ptype == NULL)
         ptype = Py_None;