Restore source code printing in Python3 exception tracebacks

Canonize tests

Restore source code printing in Python3 exception tracebacks

([arc::pullid] 413a9120-30fca745-5aba1da5-2d7bc890)

ref:7dd85c65460d342a8f1fd407ceba04b9d6c009b2

library/python/runtime_py3/importer.pxi

@@ -237,7 +237,16 @@ class BuiltinSubmoduleImporter(BuiltinImporter):
             return super().find_spec(fullname, None, target)
         else:
             return None
-
+
+
+def excepthook(*args, **kws):
+    # traceback module cannot be imported at module level, because interpreter
+    # is not fully initialized yet
+
+    import traceback
+
+    return traceback.print_exception(*args, **kws)
+
 
 sys.meta_path.insert(0, BuiltinSubmoduleImporter)
 
@@ -261,3 +270,7 @@ sys.frozen = True
 
 # Set of names of importable modules.
 sys.extra_modules = importer.memory
+
+# Use custom implementation of traceback printer.
+# Built-in printer (PyTraceBack_Print) does not support custom module loaders
+sys.excepthook = excepthook

library/python/runtime_py3/test/canondata/result.json

@@ -1,7 +1,7 @@
 {
     "test_traceback.test_traceback[custom-default]": {
         "stderr": {
-            "checksum": "26a06331e587d488b4fec501f09c7672",
+            "checksum": "6c1a9b47baa51cc6903b85fd43c529b5",
             "uri": "file://test_traceback.test_traceback_custom-default_/stderr.txt"
         },
         "stdout": {
@@ -31,7 +31,7 @@
     },
     "test_traceback.test_traceback[main-default]": {
         "stderr": {
-            "checksum": "26a06331e587d488b4fec501f09c7672",
+            "checksum": "6c1a9b47baa51cc6903b85fd43c529b5",
             "uri": "file://test_traceback.test_traceback_main-default_/stderr.txt"
         },
         "stdout": {

library/python/runtime_py3/test/canondata/test_traceback.test_traceback_custom-default_/stderr.txt

@@ -1,7 +1,12 @@
 Traceback (most recent call last):
   File "library/python/runtime_py3/test/traceback/crash.py", line 44, in main
+    one()
   File "library/python/runtime_py3/test/traceback/crash.py", line 12, in one
+    modfunc(two)  # aaa
   File "library/python/runtime_py3/test/traceback/mod/__init__.py", line 3, in modfunc
+    f()  # call back to caller
   File "library/python/runtime_py3/test/traceback/crash.py", line 16, in two
+    three(42)
   File "library/python/runtime_py3/test/traceback/crash.py", line 20, in three
+    raise RuntimeError('Kaboom! I\'m dead: {}'.format(x))
 RuntimeError: Kaboom! I'm dead: 42

library/python/runtime_py3/test/canondata/test_traceback.test_traceback_main-default_/stderr.txt

@@ -1,7 +1,12 @@
 Traceback (most recent call last):
   File "library/python/runtime_py3/test/traceback/crash.py", line 44, in main
+    one()
   File "library/python/runtime_py3/test/traceback/crash.py", line 12, in one
+    modfunc(two)  # aaa
   File "library/python/runtime_py3/test/traceback/mod/__init__.py", line 3, in modfunc
+    f()  # call back to caller
   File "library/python/runtime_py3/test/traceback/crash.py", line 16, in two
+    three(42)
   File "library/python/runtime_py3/test/traceback/crash.py", line 20, in three
+    raise RuntimeError('Kaboom! I\'m dead: {}'.format(x))
 RuntimeError: Kaboom! I'm dead: 42