bpo-32962: Backport python-gdb.py and test_gdb.py from master (GH-7726)

* bpo-32962: python-gdb catchs ValueError on read_var() (GH-7692)

python-gdb now catchs ValueError on read_var(): when Python has no
debug symbols for example.

(cherry picked from commit 019d33b7a447e78057842332fb5d3bad01922122)

* bpo-32962: python-gdb catchs UnicodeDecodeError (GH-7693)

python-gdb now catchs UnicodeDecodeError exceptions when calling
string().

(cherry picked from commit d22fc0bc7de7882da204abe50884bbde2da4f9e7)

bpo-29367: python-gdb.py now supports also method-wrapper
(wrapperobject) objects.

(cherry picked from commit 611083331d534481ca7956a376e38fb0e9ef3854)
diff --git a/Lib/test/test_gdb.py b/Lib/test/test_gdb.py
index dce3c5c..d49769e 100644
--- a/Lib/test/test_gdb.py
+++ b/Lib/test/test_gdb.py
@@ -3,13 +3,14 @@
 # The code for testing gdb was adapted from similar work in Unladen Swallow's
 # Lib/test/test_jit_gdb.py
 
+import locale
 import os
 import re
 import subprocess
 import sys
 import sysconfig
+import textwrap
 import unittest
-import sysconfig
 
 from test import test_support
 from test.test_support import run_unittest, findfile
@@ -863,7 +864,24 @@
                                           breakpoint='time_gmtime',
                                           cmds_after_breakpoint=['py-bt-full'],
                                           )
-        self.assertIn('#0 <built-in function gmtime', gdb_output)
+        self.assertIn('#1 <built-in function gmtime', gdb_output)
+
+    @unittest.skipIf(python_is_optimized(),
+                     "Python was compiled with optimizations")
+    def test_wrapper_call(self):
+        cmd = textwrap.dedent('''
+            class MyList(list):
+                def __init__(self):
+                    super(MyList, self).__init__()   # wrapper_call()
+
+            print("first break point")
+            l = MyList()
+        ''')
+        # Verify with "py-bt":
+        gdb_output = self.get_stack_trace(cmd,
+                                          cmds_after_breakpoint=['break wrapper_call', 'continue', 'py-bt'])
+        self.assertRegexpMatches(gdb_output,
+                                 r"<method-wrapper u?'__init__' of MyList object at ")
 
 
 class PyPrintTests(DebuggerTests):